










                         SENDMAILTM

              INSTALLATION AND OPERATION GUIDE

                        Eric Allman
                       Claus Assmann
                    Gregory Neil Shapiro
                      Proofpoint, Inc.


                 For Sendmail Version 8.17




     SendmailTM implements a  general  purpose  internetwork
mail  routing  facility  under the UNIX(R) operating system.
It is not tied to any one transport protocol -- its function
may  be likened to a crossbar switch, relaying messages from
one domain into another.  In the process, it can do  a  lim-
ited  amount  of  message  header editing to put the message
into a format that is appropriate for the receiving  domain.
All  of  this  is  done under the control of a configuration
file.

     Due to the requirements of  flexibility  for  sendmail,
the  configuration  file  can  seem somewhat unapproachable.
However, there are only a few basic configurations for  most
sites, for which standard configuration files have been sup-
plied.  Most other configurations can be built by  adjusting
an existing configuration file incrementally.

     Sendmail  is  based  on  RFC 821 (Simple Mail Transport
Protocol), RFC 822 (Internet Mail Headers Format),  RFC  974
(MX  routing),  RFC  1123  (Internet Host Requirements), RFC
1413 (Identification server), RFC 1652 (SMTP 8BITMIME Exten-
sion),  RFC  1869  (SMTP Service Extensions), RFC 1870 (SMTP
SIZE Extension), RFC 1891 (SMTP  Delivery  Status  Notifica-
tions), RFC 1892 (Multipart/Report), RFC 1893 (Enhanced Mail
System Status Codes), RFC 1894  (Delivery  Status  Notifica-
tions),  RFC 1985 (SMTP Service Extension for Remote Message
Queue Starting), RFC 2033 (Local Message Transmission Proto-
col),   RFC  2034  (SMTP  Service  Extension  for  Returning
____________________
   DISCLAIMER: This documentation is under modification.
   Sendmail  is  a  trademark of Proofpoint, Inc.  US Patent
Numbers 6865671, 6986037.




Sendmail Installation and Operation Guide           SMM:08-1







SMM:08-2           Sendmail Installation and Operation Guide


Enhanced Error Codes), RFC 2045 (MIME),  RFC  2476  (Message
Submission),  RFC  2487  (SMTP  Service Extension for Secure
SMTP over TLS), RFC 2554 (SMTP Service Extension for Authen-
tication),  RFC  2821  (Simple  Mail Transfer Protocol), RFC
2822 (Internet Message Format), RFC 2852  (Deliver  By  SMTP
Service  Extension),  RFC  2920  (SMTP Service Extension for
Command Pipelining), and RFC 7505 (A "Null  MX"  No  Service
Resource  Record for Domains That Accept No Mail).  However,
since sendmail is designed to work in a wider world, in many
cases it can be configured to exceed these protocols.  These
cases are described herein.

     Although sendmail is intended to run without  the  need
for monitoring, it has a number of features that may be used
to monitor or adjust the  operation  under  unusual  circum-
stances.  These features are described.

     Section  one  describes  how to do a basic sendmail in-
stallation.  Section two explains the day-to-day information
you should know to maintain your mail system.  If you have a
relatively normal site, these two  sections  should  contain
sufficient  information for you to install sendmail and keep
it happy.  Section three has information regarding the  com-
mand line arguments.  Section four describes some parameters
that may be  safely  tweaked.   Section  five  contains  the
nitty-gritty information about the configuration file.  This
section is for masochists and people who  must  write  their
own configuration file.  Section six describes configuration
that can be done at compile time.   The  appendixes  give  a
brief  but  detailed explanation of a number of features not
described in the rest of the paper.
































Sendmail Installation and Operation Guide           SMM:08-7


1.  BASIC INSTALLATION

        There are two basic steps  to  installing  sendmail.
   First,  you  have  to compile and install the binary.  If
   sendmail has already been ported to your operating system
   that should be simple.  Second, you must build a run-time
   configuration file.  This is a file that  sendmail  reads
   when  it  starts  up  that describes the mailers it knows
   about, how to parse addresses, how to rewrite the message
   header,  and  the  settings of various options.  Although
   the configuration file can be quite complex, a configura-
   tion can usually be built using an M4-based configuration
   language.  Assuming you have the standard  sendmail  dis-
   tribution, see cf/README for further information.

        The  remainder of this section will describe the in-
   stallation of sendmail assuming you can use  one  of  the
   existing  configurations  and that the standard installa-
   tion parameters are acceptable.  All pathnames and  exam-
   ples  are  given  from  the root of the sendmail subtree,
   normally /usr/src/usr.sbin/sendmail on 4.4BSD-based  sys-
   tems.

        Continue  with  the next section if you need/want to
   compile sendmail yourself.  If you have a running  binary
   already  on your system, you should probably skip to sec-
   tion 1.2.

   1.1.  Compiling Sendmail

           All sendmail source is in the sendmail  subdirec-
      tory.  To compile sendmail, "cd" into the sendmail di-
      rectory and type

          ./Build

      This will leave the binary in an  appropriately  named
      subdirectory, e.g., obj.BSD-OS.2.1.i386.  It works for
      multiple object versions compiled out of the same  di-
      rectory.

      1.1.1.  Tweaking the Build Invocation

              You  can give parameters on the Build command.
         In most cases these are only used  when  the  obj.*
         directory   is  first  created.   To  restart  from
         scratch, use -c.  These commands include:

         -L libdirs
              A list of directories to search for libraries.

         -I incdirs
              A list of directories to  search  for  include










SMM:08-8           Sendmail Installation and Operation Guide


              files.

         -E envar=value
              Set  an  environment  variable to an indicated
              value before compiling.

         -c   Create a new obj.*  tree before running.

         -f siteconfig
              Read the indicated  site  configuration  file.
              If  this parameter is not specified, Build in-
              cludes    all    of    the    files    $BUILD-
              TOOLS/Site/site.$oscf.m4      and      $BUILD-
              TOOLS/Site/site.config.m4,  where  $BUILDTOOLS
              is  normally ../devtools and $oscf is the same
              name as used on the obj.*  directory.  See be-
              low  for  a description of the site configura-
              tion file.

         -S   Skip  auto-configuration.   Build  will  avoid
              auto-detecting  libraries if this is set.  All
              libraries and map definitions must  be  speci-
              fied in the site configuration file.

         Most  other  parameters are passed to the make pro-
         gram; for details see $BUILDTOOLS/README.

      1.1.2.  Creating a Site Configuration File

              See sendmail/README  for  various  compilation
         flags  that can be set, and devtools/README for de-
         tails how to set them.

      1.1.3.  Tweaking the Makefile

              Sendmail supports two  different  formats  for
         the  local  (on disk) version of databases, notably
         the aliases database.  At least one of these should
         be defined if at all possible.

         CDB       Constant DataBase (tinycdb).

         NDBM      The  ``new  DBM''  format,  available  on
                   nearly all systems  around  today.   This
                   was the preferred format prior to 4.4BSD.
                   It allows such complex things as multiple
                   databases  and  closing  a currently open
                   database.

         NEWDB     The Berkeley DB  package.   If  you  have
                   this,  use  it.   It allows long records,
                   multiple open databases,  real  in-memory
                   caching,  and  so  forth.  You can define










Sendmail Installation and Operation Guide           SMM:08-9


                   this in conjunction with NDBM; if you do,
                   old  alias databases are read, but when a
                   new database is created  it  will  be  in
                   NEWDB  format.   As  a nasty hack, if you
                   have NEWDB, NDBM, and NIS defined, and if
                   the  alias  file  name  includes the sub-
                   string "/yp/", sendmail will create  both
                   new  and  old  versions of the alias file
                   during a newalias command.  This  is  re-
                   quired  because  the  Sun  NIS/YP  system
                   reads the DBM version of the alias  file.
                   It's ugly as sin, but it works.

         If neither of these are defined, sendmail reads the
         alias file into memory on every  invocation.   This
         can  be slow and should be avoided.  There are also
         several methods for remote database access:

         LDAP      Lightweight Directory Access Protocol.

         NIS       Sun's Network Information Services  (for-
                   merly YP).

         NISPLUS   Sun's NIS+ services.

         NETINFO   NeXT's NetInfo service.

         HESIOD    Hesiod service (from Athena).

         Other  compilation  flags  are  set  in  conf.h and
         should be predefined for you unless you are porting
         to  a  new environment.  For more options see send-
         mail/README.

      1.1.4.  Compilation and installation

              After making the  local  system  configuration
         described  above, You should be able to compile and
         install the system.  The script "Build" is the best
         approach on most systems:

             ./Build

         This  will use uname(1) to create a custom Makefile
         for your environment.

              If you are installing in the standard  places,
         you should be able to install using

             ./Build install

         This  should  install  the  binary in /usr/sbin and
         create   links   from    /usr/bin/newaliases    and










SMM:08-10          Sendmail Installation and Operation Guide


         /usr/bin/mailq to /usr/sbin/sendmail.  On most sys-
         tems it will also format  and  install  man  pages.
         Notice:  as of version 8.12 sendmail will no longer
         be installed set-user-ID root by default.   If  you
         really  want to use the old method, you can specify
         it as target:

             ./Build install-set-user-id


   1.2.  Configuration Files

           Sendmail cannot operate without  a  configuration
      file.   The  configuration  defines  the mail delivery
      mechanisms understood at  this  site,  how  to  access
      them, how to forward email to remote mail systems, and
      a number of  tuning  parameters.   This  configuration
      file  is  detailed  in the later portion of this docu-
      ment.

           The sendmail configuration  can  be  daunting  at
      first.   The world is complex, and the mail configura-
      tion reflects  that.   The  distribution  includes  an
      m4-based configuration package that hides a lot of the
      complexity.  See cf/README for details.

           Our configuration files are processed  by  m4  to
      facilitate  local  customization;  the directory cf of
      the  sendmail  distribution  directory  contains   the
      source  files.  This directory contains several subdi-
      rectories:

      cf        Both site-dependent and site-independent de-
                scriptions  of  hosts.  These can be literal
                host  names  (e.g.,  "ucbvax.mc")  when  the
                hosts  are gateways or more general descrip-
                tions (such as  "generic-solaris2.mc"  as  a
                general  description  of  an  SMTP-connected
                host running Solaris 2.x.  Files ending  .mc
                (``M4  Configuration'')  are  the  input de-
                scriptions; the output is in the correspond-
                ing  .cf  file.   The  general  structure of
                these files is described below.

      domain    Site-dependent    subdomain    descriptions.
                These  are tied to the way your organization
                wants to do addressing.   For  example,  do-
                main/CS.Berkeley.EDU.m4  is  our description
                for hosts in the CS.Berkeley.EDU  subdomain.
                These  are  referenced  using  the DOMAIN m4
                macro in the .mc file.












Sendmail Installation and Operation Guide          SMM:08-11


      feature   Definitions of specific features  that  some
                particular  host  in  your  site might want.
                These are referenced using  the  FEATURE  m4
                macro.   An  example  feature is use_cw_file
                (which   tells   sendmail   to    read    an
                /etc/mail/local-host-names  file  on startup
                to find the set of local names).

      hack      Local hacks, referenced using  the  HACK  m4
                macro.   Try  to  avoid these.  The point of
                having them here is to make  it  clear  that
                they smell.

      m4        Site-independent  m4(1)  include  files that
                have information common to all configuration
                files.   This  can  be thought of as a "#in-
                clude" directory.

      mailer    Definitions of mailers, referenced using the
                MAILER  m4 macro.  The mailer types that are
                known in this distribution are  fax,  local,
                smtp, uucp, and usenet.  For example, to in-
                clude support for  the  UUCP-based  mailers,
                use "MAILER(uucp)".

      ostype    Definitions   describing  various  operating
                system environments (such as the location of
                support  files).  These are referenced using
                the OSTYPE m4 macro.

      sh        Shell files used by the  m4  build  process.
                You shouldn't have to mess with these.

      siteconfig
                Local  UUCP  connectivity information.  This
                directory has been supplanted by  the  mail-
                ertable   feature;  any  new  configurations
                should use that  feature  to  do  UUCP  (and
                other)  routing.   The use of this directory
                is deprecated.

           If you are in a new domain (e.g., a company), you
      will probably want to create a cf/domain file for your
      domain.  This consists primarily of relay  definitions
      and  features you want enabled site-wide: for example,
      Berkeley's domain definition defines relays for BitNET
      and  UUCP.  These are specific to Berkeley, and should
      be  fully-qualified   internet-style   domain   names.
      Please  check  to make certain they are reasonable for
      your domain.

           Subdomains at Berkeley are  also  represented  in
      the  cf/domain  directory.   For  example,  the domain










SMM:08-12          Sendmail Installation and Operation Guide


      CS.Berkeley.EDU is  the  Computer  Science  subdomain,
      EECS.Berkeley.EDU  is  the  Electrical Engineering and
      Computer Sciences subdomain, and  S2K.Berkeley.EDU  is
      the Sequoia 2000 subdomain.  You will probably have to
      add an entry to this directory to be  appropriate  for
      your domain.

           You  will  have to use or create .mc files in the
      cf/cf subdirectory for your hosts.  This  is  detailed
      in the cf/README file.

   1.3.  Details of Installation Files

           This subsection describes the files that comprise
      the sendmail installation.

      1.3.1.  /usr/sbin/sendmail

              The  binary  for  sendmail   is   located   in
         /usr/sbin[1].   It  should be set-group-ID smmsp as
         described in sendmail/SECURITY.  For security  rea-
         sons,  /,  /usr,  and  /usr/sbin should be owned by
         root, mode 0755[2].

      1.3.2.  /etc/mail/sendmail.cf

              This is the main configuration file for  send-
         mail[3].   This  is one of the two non-library file
         names  compiled  into  sendmail[4],  the  other  is
         /etc/mail/submit.cf.


____________________
   [1]This is usually /usr/sbin on 4.4BSD and newer systems;
many systems install it in /usr/lib.  I understand it is  in
/usr/ucblib on System V Release 4.
   [2]Some vendors ship them owned by bin;  this  creates  a
security  hole  that  is  not  actually related to sendmail.
Other important directories  that  should  have  restrictive
ownerships   and   permissions  are  /bin,  /usr/bin,  /etc,
/etc/mail, /usr/etc, /lib, and /usr/lib.
   [3]Actually, the pathname varies depending on the operat-
ing system; /etc/mail is the preferred directory.  Some old-
er systems install it in /usr/lib/sendmail.cf, and I've also
seen it in /usr/ucblib.  If you want to move this file,  add
-D_PATH_SENDMAILCF=\"/file/name\" to the flags passed to the
C compiler.  Moving this file is not recommended: other pro-
grams and scripts know of this location.
   [4]The  system  libraries  can  reference other files; in
particular, system library subroutines that  sendmail  calls
probably reference /etc/passwd and /etc/resolv.conf.












Sendmail Installation and Operation Guide          SMM:08-13


              The configuration file is normally created us-
         ing the distribution files described above.  If you
         have  a  particularly  unusual system configuration
         you may need to create a special version.  The for-
         mat  of  this file is detailed in later sections of
         this document.

      1.3.3.  /etc/mail/submit.cf

              This is the configuration  file  for  sendmail
         when  it  is  used  for initial mail submission, in
         which case it is also called ``Mail Submission Pro-
         gram'' (MSP) in contrast to ``Mail Transfer Agent''
         (MTA).  Starting with version 8.12,  sendmail  uses
         one  of  two different configuration files based on
         its operation mode (or the  new  -A  option).   For
         initial  mail  submission,  i.e., if one of the op-
         tions -bm (default), -bs, or -t is specified,  sub-
         mit.cf is used (if available), for other operations
         sendmail.cf is used.  Details can be found in send-
         mail/SECURITY.   submit.cf is shipped with sendmail
         (in  cf/cf/)  and  is  installed  by  default.   If
         changes to the configuration need to be made, start
         with cf/cf/submit.mc and follow the instruction  in
         cf/README.

      1.3.4.  /usr/bin/newaliases

              The  newaliases  command should just be a link
         to sendmail:

             rm -f /usr/bin/newaliases
             ln -s /usr/sbin/sendmail /usr/bin/newaliases

         This can be installed in whatever search  path  you
         prefer for your system.

      1.3.5.  /usr/bin/hoststat

              The  hoststat command should just be a link to
         sendmail, in a fashion similar to newaliases.  This
         command  lists the status of the last mail transac-
         tion with all remote hosts.  The -v flag will  pre-
         vent  the  status display from being truncated.  It
         functions only when the HostStatusDirectory  option
         is set.

      1.3.6.  /usr/bin/purgestat

              This  command  is also a link to sendmail.  It
         flushes  expired  (Timeout.hoststatus)  information
         that is stored in the HostStatusDirectory tree.











SMM:08-14          Sendmail Installation and Operation Guide


      1.3.7.  /var/spool/mqueue

              The directory /var/spool/mqueue should be cre-
         ated to hold the mail queue.  This directory should
         be mode 0700 and owned by root.

              The  actual  path of this directory is defined
         by the QueueDirectory  option  of  the  sendmail.cf
         file.   To use multiple queues, supply a value end-
         ing    with    an    asterisk.     For     example,
         /var/spool/mqueue/qd*  will use all of the directo-
         ries or symbolic  links  to  directories  beginning
         with  `qd'  in  /var/spool/mqueue as queue directo-
         ries.  Do not change the queue directory  structure
         while sendmail is running.

              If  these  directories  have subdirectories or
         symbolic links to directories named `qf', `df', and
         `xf',  then  these  will  be used for the different
         queue file types.  That  is,  the  data  files  are
         stored  in  the  `df'  subdirectory, the transcript
         files are stored in the `xf' subdirectory, and  all
         others are stored in the `qf' subdirectory.

              If shared memory support is compiled in, send-
         mail stores the available  diskspace  in  a  shared
         memory segment to make the values readily available
         to all children without incurring system  overhead.
         In  this  case,  only  the daemon updates the data;
         i.e., the sendmail daemon creates the shared memory
         segment and deletes it if it is terminated.  To use
         this, sendmail must have been compiled with support
         for  shared  memory  (-DSM_CONF_SHM) and the option
         SharedMemoryKey must be set.  Notice:  do  not  use
         the  same key for sendmail invocations with differ-
         ent queue directories or different queue group dec-
         larations.   Access  to  shared  memory is not con-
         trolled by locks, i.e., there is a  race  condition
         when  data  in  the shared memory is updated.  How-
         ever, since operation of sendmail does not rely  on
         the  data in the shared memory, this does not nega-
         tively influence the behavior.

      1.3.8.  /var/spool/clientmqueue

              The directory  /var/spool/clientmqueue  should
         be  created to hold the mail queue.  This directory
         should be mode 0770 and owned by user smmsp,  group
         smmsp.

              The  actual  path of this directory is defined
         by the QueueDirectory option of the submit.cf file.











Sendmail Installation and Operation Guide          SMM:08-15


      1.3.9.  /var/spool/mqueue/.hoststat

              This is a typical value for the  HostStatusDi-
         rectory  option,  containing one file per host that
         this sendmail has chatted  with  recently.   It  is
         normally a subdirectory of mqueue.

      1.3.10.  /etc/mail/aliases*

              The     system    aliases    are    held    in
         "/etc/mail/aliases".  A sample is given  in  "send-
         mail/aliases"  which  includes  some  aliases which
         must be defined:

             cp sendmail/aliases /etc/mail/aliases
             edit /etc/mail/aliases

         You should extend this file with any  aliases  that
         are apropos to your system.

              Normally  sendmail looks at a database version
         of     the     files,     stored     either      in
         "/etc/mail/aliases.dir" and "/etc/mail/aliases.pag"
         or "/etc/mail/aliases.db" depending on which  data-
         base  package  you  are  using.  The actual path of
         this file is defined in the AliasFile option of the
         sendmail.cf file.

              The  permissions  of  the  alias  file and the
         database versions should be 0640 to  prevent  local
         denial  of  service attacks as explained in the top
         level README in the sendmail distribution.  If  the
         permissions  0640  are  used,  be  sure  that  only
         trusted users belong to the group assigned to those
         files.   Otherwise,  files should not even be group
         readable.

      1.3.11.  /etc/rc or /etc/init.d/sendmail

              It will be necessary to start up the  sendmail
         daemon  when your system reboots.  This daemon per-
         forms two functions: it listens on the SMTP  socket
         for connections (to receive mail from a remote sys-
         tem) and it processes the queue periodically to in-
         sure that mail gets delivered when hosts come up.

              If  necessary,  add  the  following  lines  to
         "/etc/rc" (or "/etc/rc.local"  as  appropriate)  in
         the  area  where it is starting up the daemons on a
         BSD-base system, or on a System-V-based  system  in
         one     of    the    startup    files,    typically
         "/etc/init.d/sendmail":











SMM:08-16          Sendmail Installation and Operation Guide


             if [ -f /usr/sbin/sendmail -a -f /etc/mail/sendmail.cf ]; then
                  (cd /var/spool/mqueue; rm -f xf*)
                  /usr/sbin/sendmail -bd -q30m &
                  echo -n ' sendmail' >/dev/console
             fi

         The "cd" and "rm" commands insure  that  all  tran-
         script  files  have  been removed; extraneous tran-
         script files may be left around if the system  goes
         down  in  the  middle of processing a message.  The
         line that actually invokes sendmail has two  flags:
         "-bd"  causes  it  to  listen on the SMTP port, and
         "-q30m" causes it to run the queue every half hour.

              Some people use a more complex startup script,
         removing  zero  length  qf/hf/Qf files and df files
         for which there is no qf/hf/Qf file.  Note this  is
         not  advisable.   For  example, see Figure 1 for an
         example of a complex script which does  this  clean
         up.

      1.3.12.  /etc/mail/helpfile

              This  is  the  help file used by the SMTP HELP
         command.  It should be copied from  "sendmail/help-
         file":

             cp sendmail/helpfile /etc/mail/helpfile

         The  actual  path  of  this  file is defined in the
         HelpFile option of the sendmail.cf file.

      1.3.13.  /etc/mail/statistics

              If you wish to collect statistics  about  your
         mail   traffic,   you   should   create   the  file
         "/etc/mail/statistics":

             cp /dev/null /etc/mail/statistics
             chmod 0600 /etc/mail/statistics

         This file does not grow.  It is  printed  with  the
         program  "mailstats/mailstats.c."   The actual path
         of this file is defined in  the  S  option  of  the
         sendmail.cf file.

      1.3.14.  /usr/bin/mailq

              If  sendmail  is  invoked  as "mailq," it will
         simulate the -bp flag (i.e.,  sendmail  will  print
         the  contents  of the mail queue; see below).  This
         should be a link to /usr/sbin/sendmail.











Sendmail Installation and Operation Guide          SMM:08-17



____________________________________________________________

#!/bin/sh
# remove zero length qf/hf/Qf files
for qffile in qf* hf* Qf*
do
     if [ -r $qffile ]
     then
          if [ ! -s $qffile ]
          then
               echo -n " <zero: $qffile>" > /dev/console
               rm -f $qffile
          fi
     fi
done
# rename tf files to be qf if the qf does not exist
for tffile in tf*
do
     qffile=`echo $tffile | sed 's/t/q/'`
     if [ -r $tffile -a ! -f $qffile ]
     then
          echo -n " <recovering: $tffile>" > /dev/console
          mv $tffile $qffile
     else
          if [ -f $tffile ]
          then
               echo -n " <extra: $tffile>" > /dev/console
               rm -f $tffile
          fi
     fi
done
# remove df files with no corresponding qf/hf/Qf files
for dffile in df*
do
     qffile=`echo $dffile | sed 's/d/q/'`
     hffile=`echo $dffile | sed 's/d/h/'`
     Qffile=`echo $dffile | sed 's/d/Q/'`
     if [ -r $dffile -a ! -f $qffile -a ! -f $hffile -a ! -f $Qffile ]
     then
          echo -n " <incomplete: $dffile>" > /dev/console
          mv $dffile `echo $dffile | sed 's/d/D/'`
     fi
done
# announce files that have been saved during disaster recovery
for xffile in [A-Z]f*
do
     if [ -f $xffile ]
     then
          echo -n " <panic: $xffile>" > /dev/console
     fi
done











SMM:08-18          Sendmail Installation and Operation Guide


            Figure 1 -- A complex startup script
____________________________________________________________


      1.3.15.  sendmail.pid

              sendmail stores its current pid  in  the  file
         specified   by   the  PidFile  option  (default  is
         _PATH_SENDMAILPID).   sendmail  uses   TempFileMode
         (which defaults to 0600) as the permissions of that
         file to prevent local denial of service attacks  as
         explained  in  the top level README in the sendmail
         distribution.  If the file already exists, then  it
         might  be  necessary  to change the permissions ac-
         cordingly, e.g.,

             chmod 0600 /var/run/sendmail.pid

         Note that as of version 8.13, this file is unlinked
         when sendmail exits.  As a result of this change, a
         script such as the following, which may have worked
         prior to 8.13, will no longer work:

             # stop & start sendmail
             PIDFILE=/var/run/sendmail.pid
             kill `head -1 $PIDFILE`
             `tail -1 $PIDFILE`

         because  it assumes that the pidfile will still ex-
         ist even after killing  the  process  to  which  it
         refers.   Below  is  a  script which will work cor-
         rectly on both newer and older versions:

             # stop & start sendmail
             PIDFILE=/var/run/sendmail.pid
             pid=`head -1 $PIDFILE`
             cmd=`tail -1 $PIDFILE`
             kill $pid
             $cmd

         This is just an example script, it does not perform
         any  error checks, e.g., whether the pidfile exists
         at all.

      1.3.16.  Map Files

              To prevent local denial of service attacks  as
         explained  in  the top level README in the sendmail
         distribution, the permissions of map files  created
         by makemap should be 0640.  The use of 0640 implies
         that only trusted users belong  to  the  group  as-
         signed  to those files.  If those files already ex-
         ist, then it  might  be  necessary  to  change  the










Sendmail Installation and Operation Guide          SMM:08-19


         permissions accordingly, e.g.,

             cd /etc/mail
             chmod 0640 *.db *.pag *.dir


2.  NORMAL OPERATIONS

   2.1.  The System Log

           The  system  log  is  supported by the syslogd(8)
      program.  All messages from sendmail are logged  under
      the LOG_MAIL facility[5].

      2.1.1.  Format

              Each line in the  system  log  consists  of  a
         timestamp,  the  name of the machine that generated
         it (for logging from several machines over the  lo-
         cal area network), the word "sendmail:", and a mes-
         sage[6].    Most   messages   are   a  sequence  of
         name=value pairs.

              The two most common lines are  logged  when  a
         message  is  processed.  The first logs the receipt
         of a message; there will be exactly  one  of  these
         per message.  Some fields may be omitted if they do
         not contain interesting information.  Fields are:

         from      The envelope sender address.

         size      The size of the message in bytes.

         class     The class (i.e., numeric  precedence)  of
                   the message.

         pri       The  initial  message  priority (used for
                   queue sorting).

         nrcpts    The number  of  envelope  recipients  for
                   this message (after aliasing and forward-
                   ing).

         msgid     The message id of the message  (from  the
                   header).

____________________
   [5]Except on Ultrix, which does not support facilities in
the syslog.
   [6]This format may  vary  slightly  if  your  vendor  has
changed the syntax.












SMM:08-20          Sendmail Installation and Operation Guide


         bodytype  The message body type (7BIT or 8BITMIME),
                   as determined from the envelope.

         proto     The protocol used to receive this message
                   (e.g., ESMTP or UUCP)

         daemon    The  daemon  name  from the DaemonPortOp-
                   tions setting.

         relay     The machine from which it was received.

         There is also one line logged per delivery  attempt
         (so there can be several per message if delivery is
         deferred or there are multiple recipients).  Fields
         are:

         to        A  comma-separated list of the recipients
                   to this mailer.

         ctladdr   The ``controlling user'',  that  is,  the
                   name of the user whose credentials we use
                   for delivery.

         delay     The total delay  between  the  time  this
                   message  was received and the current de-
                   livery attempt.

         xdelay    The amount of time needed in this  deliv-
                   ery  attempt  (normally indicative of the
                   speed of the connection).

         mailer    The name of the mailer used to deliver to
                   this recipient.

         relay     The  name  of  the host that actually ac-
                   cepted (or rejected) this recipient.

         dsn       The enhanced error  code  (RFC  2034)  if
                   available.

         stat      The delivery status.

         Not all fields are present in all messages; for ex-
         ample, the relay is usually not  listed  for  local
         deliveries.

      2.1.2.  Levels

              If  you  have  syslogd(8) or an equivalent in-
         stalled, you will be able to do logging.  There  is
         a  large  amount of information that can be logged.
         The log is arranged as a succession of levels.   At
         the  lowest level only extremely strange situations










Sendmail Installation and Operation Guide          SMM:08-21


         are logged.  At the highest level,  even  the  most
         mundane  and  uninteresting events are recorded for
         posterity.  As a convention, log levels  under  ten
         are considered generally "useful;" log levels above
         64 are reserved  for  debugging  purposes.   Levels
         from  11-64  are  reserved  for verbose information
         that some sites might want.

              A complete description of the  log  levels  is
         given in section ``Log Level''.

   2.2.  Dumping State

           You  can  ask  sendmail to log a dump of the open
      files and the connection cache by sending it a SIGUSR1
      signal.  The results are logged at LOG_DEBUG priority.

   2.3.  The Mail Queues

           Mail messages may either be delivered immediately
      or be held for  later  delivery.   Held  messages  are
      placed into a holding directory called a mail queue.

           A mail message may be queued for these reasons:

       + If  a mail message is temporarily undeliverable, it
         is queued and delivery is attempted later.  If  the
         message  is addressed to multiple recipients, it is
         queued only for those recipients to  whom  delivery
         is not immediately possible.
       + If  the  SuperSafe  option is set to true, all mail
         messages are queued while delivery is attempted.
       + If the DeliveryMode option is set to queue-only  or
         defer,  all mail is queued, and no immediate deliv-
         ery is attempted.
       + If the load average becomes higher than  the  value
         of  the  QueueLA option and the QueueFactor (q) op-
         tion divided by the difference in the current  load
         average  and  the  QueueLA  option plus one is less
         than the priority  of  the  message,  messages  are
         queued rather than immediately delivered.
       + One  or  more addresses are marked as expensive and
         delivery is postponed until the next queue  run  or
         one  or  more address are marked as held via mailer
         which uses the hold mailer flag.
       + The mail message has been marked as quarantined via
         a mail filter or rulesets.

      2.3.1.  Queue Groups and Queue Directories

              There  are one or more mail queues.  Each mail
         queue belongs to a queue group.  There is always  a
         default  queue  group  that  is  called  ``mqueue''










SMM:08-22          Sendmail Installation and Operation Guide


         (which is where messages go by default unless  oth-
         erwise  specified).   The  directory or directories
         which comprise the default queue group  are  speci-
         fied  by the QueueDirectory option.  There are zero
         or more additional named queue groups declared  us-
         ing the Q command in the configuration file.

              By  default, a queued message is placed in the
         queue group associated with the first recipient  in
         the  recipient list.  A recipient address is mapped
         to a queue group as follows.  First, if there is  a
         ruleset  called ``queuegroup'', and if this ruleset
         maps the address to a queue group name,  then  that
         queue  group  is chosen.  That is, the argument for
         the ruleset is the recipient address (i.e., the ad-
         dress  part  of the resolved triple) and the result
         should be $# followed by the name of a queue group.
         Otherwise,  if  the  mailer associated with the ad-
         dress specifies a  queue  group,  then  that  queue
         group  is  chosen.   Otherwise,  the  default queue
         group is chosen.

              A message with  multiple  recipients  will  be
         split  if  different queue groups are chosen by the
         mapping of recipients to queue groups.

              When a message is placed in a queue group, and
         the queue group has more than one queue, a queue is
         selected randomly.

              If  a  message  with  multiple  recipients  is
         placed into a queue group with the 'r' option (max-
         imum number of recipients per  message)  set  to  a
         positive  value N, and if there are more than N re-
         cipients in the message, then the message  will  be
         split into multiple messages, each of which have at
         most N recipients.

              Notice: if multiple queue groups are used,  do
         not move queue files around, e.g., into a different
         queue directory.  This may have weird  effects  and
         can  cause  mail  not to be delivered.  Queue files
         and directories should be  treated  as  opaque  and
         should not be manipulated directly.

      2.3.2.  Queue Runs

              sendmail has two different ways to process the
         queue(s).  The first one is to start queue  runners
         after certain intervals (``normal'' queue runners),
         the second one is to keep  queue  runner  processes
         around  (``persistent'' queue runners).  How to se-
         lect either of these  types  is  discussed  in  the










Sendmail Installation and Operation Guide          SMM:08-23


         appendix  ``COMMAND LINE FLAGS''.  Persistent queue
         runners have the advantage that  no  new  processes
         need  to be spawned at certain intervals; they just
         sleep for a specified time after  they  finished  a
         queue  run.   Another advantage of persistent queue
         runners is that only one  process  belonging  to  a
         workgroup  (a  workgroup  is a set of queue groups)
         collects the data for a queue run and then multiple
         queue  runner  may  go ahead using that data.  This
         can significantly reduce the disk I/O necessary  to
         read  the queue files compared to starting multiple
         queue runners directly.  Their disadvantage is that
         a  new  queue  run  is only started after all queue
         runners belonging to a group finished their  tasks.
         In  case one of the queue runners tries delivery to
         a slow recipient site at the end of  a  queue  run,
         the  next  queue  run may be substantially delayed.
         In general this should be smoothed out due  to  the
         distribution of those slow jobs, however, for sites
         with small number of queue entries this  might  in-
         troduce  noticeable delays.  In general, persistent
         queue runners are only useful for  sites  with  big
         queues.

      2.3.3.  Manual Intervention

              Under normal conditions the mail queue will be
         processed transparently.   However,  you  may  find
         that  manual  intervention  is sometimes necessary.
         For example, if a major host is down for  a  period
         of  time  the  queue  may become clogged.  Although
         sendmail ought to recover gracefully when the  host
         comes up, you may find performance unacceptably bad
         in the meantime.  In that case you  want  to  check
         the  content  of the queue and manipulate it as ex-
         plained in the next two sections.

      2.3.4.  Printing the queue

              The contents of the queue(s)  can  be  printed
         using  the  mailq command (or by specifying the -bp
         flag to sendmail):

             mailq

         This will produce a listing of the queue id's,  the
         size  of  the message, the date the message entered
         the queue,  and  the  sender  and  recipients.   If
         shared  memory support is compiled in, the flag -bP
         can be used to print the number of entries  in  the
         queue(s),  provided  a  process  updates  the data.
         However, as explained earlier, the output might  be
         slightly  wrong,  since access to the shared memory










SMM:08-24          Sendmail Installation and Operation Guide


         is not locked.  For example,  ``unknown  number  of
         entries''  might  be  shown.  The internal counters
         are updated after each queue  run  to  the  correct
         value again.

      2.3.5.  Forcing the queue

              Sendmail should run the queue automatically at
         intervals.  When using multiple queues, a  separate
         process  will  by default be created to run each of
         the queues unless the queue run is initiated  by  a
         user  with  the  verbose flag.  The algorithm is to
         read and sort the queue, and  then  to  attempt  to
         process all jobs in order.  When it attempts to run
         the job, sendmail first checks to see if the job is
         locked.  If so, it ignores the job.

              There  is  no  attempt to insure that only one
         queue processor exists at any time, since there  is
         no  guarantee  that  a  job  cannot take forever to
         process (however, sendmail does include  heuristics
         to try to abort jobs that are taking absurd amounts
         of time; technically, this violates RFC 821, but is
         blessed  by  RFC  1123).   Due to the locking algo-
         rithm, it is impossible for one job to  freeze  the
         entire  queue.  However, an uncooperative recipient
         host or a program recipient that never returns  can
         accumulate many processes in your system.  Unfortu-
         nately, there is no completely general way to solve
         this.

              In  some cases, you may find that a major host
         going down for a couple of days may create  a  pro-
         hibitively  large queue.  This will result in send-
         mail spending an inordinate amount of time  sorting
         the  queue.   This situation can be fixed by moving
         the queue to a temporary place and creating  a  new
         queue.  The old queue can be run later when the of-
         fending host returns to service.

              To do this, it is acceptable to move  the  en-
         tire queue directory:

             cd /var/spool
             mv mqueue omqueue; mkdir mqueue; chmod 0700 mqueue

         You  should then kill the existing daemon (since it
         will still be processing in the  old  queue  direc-
         tory) and create a new daemon.

              To run the old mail queue, issue the following
         command:











Sendmail Installation and Operation Guide          SMM:08-25


             /usr/sbin/sendmail -C /etc/mail/queue.cf -q

         The -C flag specifies  an  alternate  configuration
         file queue.cf which should refer to the moved queue
         directory

             O QueueDirectory=/var/spool/omqueue

         and the -q flag says to just run every job  in  the
         queue.  You can also specify the moved queue direc-
         tory on the command line

             /usr/sbin/sendmail -oQ/var/spool/omqueue -q

         but this requires that you do not have queue groups
         in  the  configuration  file, because those are not
         subdirectories of the  moved  directory.   See  the
         section  about  ``Queue Group Declaration'' for de-
         tails; you most likely need a different  configura-
         tion  file  to  correctly  deal  with this problem.
         However, a proper  configuration  of  queue  groups
         should  avoid  filling up queue directories, so you
         shouldn't run into this problem.   If  you  have  a
         tendency  toward voyeurism, you can use the -v flag
         to watch what is going on.

              When the queue is finally emptied, you can re-
         move the directory:

             rmdir /var/spool/omqueue


      2.3.6.  Quarantined Queue Items

              It  is possible to "quarantine" mail messages,
         otherwise known  as  envelopes.   Envelopes  (queue
         files)  are  stored but not considered for delivery
         or display unless the "quarantine" state of the en-
         velope  is undone or delivery or display of quaran-
         tined items is requested.  Quarantined messages are
         tagged  by  using  a  different  name for the queue
         file, 'hf' instead of 'qf', and by adding the quar-
         antine reason to the queue file.

              Delivery  or  display of quarantined items can
         be requested using the  -qQ  flag  to  sendmail  or
         mailq.  Additionally, messages already in the queue
         can be quarantined or unquarantined using  the  new
         -Q flag to sendmail.  For example,

             sendmail -Qreason -q[!][I|R|S][matchstring]

         Quarantines  the  normal  queue  items matching the










SMM:08-26          Sendmail Installation and Operation Guide


         criteria specified by the -q[!][I|R|S][matchstring]
         using the reason given on the -Q flag.  Likewise,

             sendmail -qQ -Q[reason] -q[!][I|R|S|Q][matchstring]

         Change  the  quarantine  reason for the quarantined
         items  matching  the  criteria  specified  by   the
         -q[!][I|R|S|Q][matchstring]  using the reason given
         on the -Q flag.  If there is no reason,
          unquarantine the matching items and make them nor-
         mal  queue  items.   Note  that  the -qQ flag tells
         sendmail to operate on quarantined items instead of
         normal items.

   2.4.  Disk Based Connection Information

           Sendmail  stores  a  large  amount of information
      about each remote system it has connected to  in  mem-
      ory.  It is possible to preserve some of this informa-
      tion on disk as well, by using the HostStatusDirectory
      option, so that it may be shared between several invo-
      cations of sendmail.  This allows mail  to  be  queued
      immediately or skipped during a queue run if there has
      been a recent failure in connecting to  a  remote  ma-
      chine.   Note:  information  about  a remote system is
      stored in a file whose pathname consists of the compo-
      nents  of the hostname in reverse order.  For example,
      the information  for  host.example.com  is  stored  in
      com./example./host.   For  top-level  domains like com
      this can create a large number of subdirectories which
      on  some  filesystems  can exhaust some limits.  More-
      over, the performance of  lookups  in  directory  with
      thousands  of  entries can be fairly slow depending on
      the filesystem implementation.

           Additionally  enabling  SingleThreadDelivery  has
      the  added effect of single-threading mail delivery to
      a destination.  This can be quite helpful if  the  re-
      mote  machine is running an SMTP server that is easily
      overloaded or cannot accept more than a single connec-
      tion  at  a  time,  but  can cause some messages to be
      punted to a future queue run.  It also applies to  all
      hosts, so setting this because you have one machine on
      site that runs some software that  is  easily  overrun
      can  cause  mail to other hosts to be slowed down.  If
      this option is set, you probably want to set the  Min-
      QueueAge  option as well and run the queue fairly fre-
      quently; this way jobs that are  skipped  because  an-
      other  sendmail  is  talking  to the same host will be
      tried again quickly rather than being  delayed  for  a
      long time.












Sendmail Installation and Operation Guide          SMM:08-27


           The  disk  based  host information is stored in a
      subdirectory of the  mqueue  directory  called  .host-
      stat[7].   Removing this directory and its subdirecto-
      ries has an effect similar to  the  purgestat  command
      and  is  completely safe.  However, purgestat only re-
      moves expired (Timeout.hoststatus) data.  The informa-
      tion  in  these  directories  can  be perused with the
      hoststat command, which will indicate the  host  name,
      the  last  access,  and the status of that access.  An
      asterisk in the left  most  column  indicates  that  a
      sendmail  process  currently  has  the host locked for
      mail delivery.

           The disk based connection information is  treated
      the  same  way  as memory based connection information
      for the purpose of timeouts.  By default,  information
      about host failures is valid for 30 minutes.  This can
      be adjusted with the Timeout.hoststatus option.

           The connection information stored on disk may  be
      expired  at  any time with the purgestat command or by
      invoking sendmail with the -bH switch.  The connection
      information may be viewed with the hoststat command or
      by invoking sendmail with the -bh switch.

   2.5.  The Service Switch

           The implementation  of  certain  system  services
      such as host and user name lookup is controlled by the
      service switch.  If the host operating system supports
      such  a  switch, and sendmail knows about it, sendmail
      will use the native version.  Ultrix, Solaris, and DEC
      OSF/1 are examples of such systems[8].

           If  the underlying operating system does not sup-
      port a service switch (e.g., SunOS  4.X,  HP-UX,  BSD)
      then sendmail will provide a stub implementation.  The
      ServiceSwitchFile option points to the name of a  file
      that  has  the service definitions.  Each line has the
      name of a service and the possible implementations  of
      that service.  For example, the file:

          hosts     dns files nis
          aliases   files nis
____________________
   [7]This is the usual value of the HostStatusDirectory op-
tion; it can, of  course,  go  anywhere  you  like  in  your
filesystem.
   [8]HP-UX  10  has  service  switch support, but since the
APIs are apparently not available in the libraries  sendmail
does not use the native service switch in this release.












SMM:08-28          Sendmail Installation and Operation Guide


      will ask sendmail to look for hosts in the Domain Name
      System first.  If  the  requested  host  name  is  not
      found,  it  tries  local  files,  and if that fails it
      tries NIS.  Similarly, when  looking  for  aliases  it
      will try the local files first followed by NIS.

           Notice: since sendmail must access MX records for
      correct operation, it will use DNS if it is configured
      in the ServiceSwitchFile file.  Hence an entry like

          hosts     files dns

      will not avoid DNS lookups even if a host can be found
      in /etc/hosts.

           Note: in contrast to the sendmail stub  implemen-
      tation  some  operating systems do not preserve tempo-
      rary  failures.   For  example,  if  DNS   returns   a
      TRY_AGAIN status for this setup

          hosts     files dns myhostname

      but myhostname does not find the requested entry, then
      a permanent error is returned to sendmail which  obvi-
      ously  can  cause  problems, e.g., an immediate bounce
      instead of a deferral.

           Service switches are not  completely  integrated.
      For  example,  despite  the  fact  that the host entry
      listed in the above example specifies to look in  NIS,
      on  SunOS  this won't happen because the system imple-
      mentation of gethostbyname(3) doesn't understand this.

   2.6.  The Alias Database

           After recipient addresses are read from the  SMTP
      connection  or command line they are parsed by ruleset
      0, which must resolve to  a  {mailer,  host,  address}
      triple.   If  the flags selected by the mailer include
      the A (aliasable) flag, the address part of the triple
      is  looked up as the key (i.e., the left hand side) in
      the alias database.  If there is a match, the  address
      is  deleted  from  the send queue and all addresses on
      the right hand side of the alias are added in place of
      the  alias that was found.  This is a recursive opera-
      tion, so aliases found in the right hand side  of  the
      alias are similarly expanded.

           The alias database exists in two forms.  One is a
      text form, maintained in the  file  /etc/mail/aliases.
      The aliases are of the form

          name: name1, name2, ...










Sendmail Installation and Operation Guide          SMM:08-29


      Only local names may be aliased; e.g.,

          eric@prep.ai.MIT.EDU: eric@CS.Berkeley.EDU

      will   not   have   the   desired  effect  (except  on
      prep.ai.MIT.EDU, and they probably don't want  me)[9].
      Aliases  may be continued by starting any continuation
      lines with a space or a tab or by putting a  backslash
      directly  before  the  newline.  Blank lines and lines
      beginning with a sharp sign ("#") are comments.

           The second form is processed by  the  ndbm(3)[10]
      or  the Berkeley DB library.  This form is in the file
      /etc/mail/aliases.db    (if    using     NEWDB)     or
      /etc/mail/aliases.dir  and  /etc/mail/aliases.pag  (if
      using NDBM).  This is the form that sendmail  actually
      uses  to  resolve  aliases.  This technique is used to
      improve performance.

           The control of search order is  actually  set  by
      the service switch.  Essentially, the entry

          O AliasFile=switch:aliases

      is  always  added  as the first alias entry; also, the
      first alias file name without a class  (e.g.,  without
      "nis:"  on  the front) will be used as the name of the
      file for a ``files'' entry in the aliases switch.  For
      example, if the configuration file contains

          O AliasFile=/etc/mail/aliases

      and the service switch contains

          aliases   nis files nisplus

      then  aliases  will first be searched in the NIS data-
      base, then in  /etc/mail/aliases,  then  in  the  NIS+
      database.

           You  can also use NIS-based alias files.  For ex-
      ample, the specification:

          O AliasFile=/etc/mail/aliases
          O AliasFile=nis:mail.aliases@my.nis.domain

____________________
   [9]Actually, any mailer that has the `A' mailer flag  set
will  permit aliasing; this is normally limited to the local
mailer.
   [10]The gdbm package does not work.












SMM:08-30          Sendmail Installation and Operation Guide


      will first search the /etc/mail/aliases file and  then
      the   map  named  "mail.aliases"  in  "my.nis.domain".
      Warning: if you build your own NIS-based alias  files,
      be  sure  to  provide the -l flag to makedbm(8) to map
      upper case letters in the keys to lower  case;  other-
      wise,  aliases  with upper case letters in their names
      won't match incoming addresses.

           Additional flags can be added after the colon ex-
      actly like a K line -- for example:

          O AliasFile=nis:-N mail.aliases@my.nis.domain

      will search the appropriate NIS map and always include
      null bytes in the key.  Also:

          O AliasFile=nis:-f mail.aliases@my.nis.domain

      will prevent sendmail from downcasing the  key  before
      the alias lookup.

      2.6.1.  Rebuilding the alias database

              The hash or dbm version of the database may be
         rebuilt explicitly by executing the command

             newaliases

         This is equivalent to giving sendmail the -bi flag:

             /usr/sbin/sendmail -bi


              If you have multiple aliases databases  speci-
         fied,  the -bi flag rebuilds all the database types
         it understands (for example, it  can  rebuild  NDBM
         databases but not NIS databases).

      2.6.2.  Potential problems

              There  are a number of problems that can occur
         with the alias database.  They all  result  from  a
         sendmail process accessing the DBM version while it
         is only partially built.  This can happen under two
         circumstances:  One  process  accesses the database
         while another process  is  rebuilding  it,  or  the
         process  rebuilding the database dies (due to being
         killed or a system crash) before completing the re-
         build.

              Sendmail  has  three  techniques to try to re-
         lieve these problems.  First, it ignores interrupts
         while  rebuilding  the  database;  this  avoids the










Sendmail Installation and Operation Guide          SMM:08-31


         problem of someone aborting the process  leaving  a
         partially  rebuilt  database.  Second, it locks the
         database source file during the rebuild -- but that
         may not work over NFS or if the file is unwritable.
         Third, at the end of the rebuild it adds  an  alias
         of the form

             @: @

         (which  is  not  normally  legal).  Before sendmail
         will access the database, it checks to insure  that
         this entry exists[11].

      2.6.3.  List owners

              If an error occurs on sending to a certain ad-
         dress, say "x", sendmail will look for an alias  of
         the  form "owner-x" to receive the errors.  This is
         typically useful for a mailing list where the  sub-
         mitter  of the list has no control over the mainte-
         nance of the list itself; in  this  case  the  list
         maintainer would be the owner of the list.  For ex-
         ample:

             unix-wizards: eric@ucbarpa, wnj@monet, nosuchuser,
                  sam@matisse
             owner-unix-wizards: unix-wizards-request
             unix-wizards-request: eric@ucbarpa

         would cause "eric@ucbarpa" to get  the  error  that
         will  occur  when someone sends to unix-wizards due
         to the inclusion of "nosuchuser" on the list.

              List owners also cause the envelope sender ad-
         dress  to  be  modified.  The contents of the owner
         alias are used if they point to a single user, oth-
         erwise  the  name of the alias itself is used.  For
         this reason, and to obey Internet conventions,  the
         "owner-"  address normally points at the "-request"
         address; this causes messages to go  out  with  the
         typical  Internet  convention  of  using ``list-re-
         quest'' as the return address.

   2.7.  User Information Database

           This option is deprecated, use virtusertable  and
      genericstable  instead  as explained in cf/README.  If
____________________
   [11]The AliasWait option is required in the configuration
for this action to occur.  This should  normally  be  speci-
fied.












SMM:08-32          Sendmail Installation and Operation Guide


      you have a version of sendmail with the user  informa-
      tion  database compiled in, and you have specified one
      or more databases using the U  option,  the  databases
      will be searched for a user:maildrop entry.  If found,
      the mail will be sent to the specified address.

   2.8.  Per-User Forwarding (.forward Files)

           As an alternative to the alias database, any user
      may  put a file with the name ".forward" in his or her
      home directory.  If this file exists,  sendmail  redi-
      rects  mail  for  that  user  to the list of addresses
      listed in the .forward file.  Note  that  aliases  are
      fully  expanded  before  forward files are referenced.
      For example, if the home directory for user "mckusick"
      has a .forward file with contents:

          mckusick@ernie
          kirk@calder

      then  any  mail  arriving for "mckusick" will be redi-
      rected to the specified accounts.

           Actually, the configuration file  defines  a  se-
      quence of filenames to check.  By default, this is the
      user's .forward file, but can be defined  to  be  more
      generally using the ForwardPath option.  If you change
      this, you will have to inform your user  base  of  the
      change;  .forward is pretty well incorporated into the
      collective subconscious.

   2.9.  Special Header Lines

           Several header lines have special interpretations
      defined by the configuration file.  Others have inter-
      pretations built into sendmail that cannot be  changed
      without  changing  the  code.  These built-ins are de-
      scribed here.

      2.9.1.  Errors-To:

              If errors occur  anywhere  during  processing,
         this  header will cause error messages to go to the
         listed addresses.  This  is  intended  for  mailing
         lists.

              The  Errors-To:  header was created in the bad
         old days when UUCP didn't understand  the  distinc-
         tion  between  an envelope and a header; this was a
         hack to provide what should now be  passed  as  the
         envelope sender address.  It should go away.  It is
         only used if the UseErrorsTo option is set.











Sendmail Installation and Operation Guide          SMM:08-33


              The Errors-To: header is officially deprecated
         and will go away in a future release.

      2.9.2.  Apparently-To:

              RFC  822 requires at least one recipient field
         (To:, Cc:, or Bcc: line) in every  message.   If  a
         message  comes  in with no recipients listed in the
         message then sendmail will adjust the header  based
         on the "NoRecipientAction" option.  One of the pos-
         sible actions is to add an "Apparently-To:"  header
         line for any recipients it is aware of.

              The  Apparently-To: header is non-standard and
         is both deprecated and strongly discouraged.

      2.9.3.  Precedence

              The Precedence: header can be used as a  crude
         control  of  message  priority.  It tweaks the sort
         order in the queue and can be configured to  change
         the  message  timeout  values.  The precedence of a
         message also controls how delivery status notifica-
         tions (DSNs) are processed for that message.

   2.10.  IDENT Protocol Support

           Sendmail  supports  the IDENT protocol as defined
      in RFC 1413.  Note that the RFC states a client should
      wait  at least 30 seconds for a response.  The default
      Timeout.ident is 5 seconds as many sites have  adopted
      the practice of dropping IDENT queries.  This has lead
      to delays processing  mail.   Although  this  enhances
      identification  of  the  author of an email message by
      doing a ``call back'' to the originating system to in-
      clude  the owner of a particular TCP connection in the
      audit trail it is in no sense  perfect;  a  determined
      forger  can easily spoof the IDENT protocol.  The fol-
      lowing description is excerpted from RFC 1413:

           6.  Security Considerations

           The information returned by this protocol  is  at
           most  as  trustworthy as the host providing it OR
           the organization operating the host.   For  exam-
           ple,  a PC in an open lab has few if any controls
           on it to prevent a user from having this protocol
           return  any identifier the user wants.  Likewise,
           if the host has been compromised the  information
           returned may be completely erroneous and mislead-
           ing.












SMM:08-34          Sendmail Installation and Operation Guide


           The Identification Protocol is not intended as an
           authorization  or  access  control  protocol.  At
           best, it provides some additional auditing infor-
           mation  with  respect  to  TCP  connections.   At
           worst, it can provide misleading,  incorrect,  or
           maliciously incorrect information.

           The  use of the information returned by this pro-
           tocol for other than auditing  is  strongly  dis-
           couraged.    Specifically,  using  Identification
           Protocol information to make access control deci-
           sions  -  either  as the primary method (i.e., no
           other checks) or as an adjunct to  other  methods
           may  result  in  a weakening of normal host secu-
           rity.

           An Identification server may  reveal  information
           about users, entities, objects or processes which
           might normally be considered private.  An Identi-
           fication server provides service which is a rough
           analog of the CallerID services provided by  some
           phone companies and many of the same privacy con-
           siderations and arguments that apply to the  Cal-
           lerID  service  apply  to Identification.  If you
           wouldn't run a "finger"  server  due  to  privacy
           considerations  you may not want to run this pro-
           tocol.

      In some cases your system may not work  properly  with
      IDENT  support  due to a bug in the TCP/IP implementa-
      tion.  The symptoms will be that for  some  hosts  the
      SMTP connection will be closed almost immediately.  If
      this is true or if you do not want to use  IDENT,  you
      should  set  the IDENT timeout to zero; this will dis-
      able the IDENT protocol.

3.  ARGUMENTS

        The complete list of arguments to  sendmail  is  de-
   scribed  in  detail  in Appendix A.  Some important argu-
   ments are described here.

   3.1.  Queue Interval

           The amount of time between forking a  process  to
      run  through  the queue is defined by the -q flag.  If
      you run with delivery mode set to i or b this  can  be
      relatively  large, since it will only be relevant when
      a host that was down comes back up.  If you run  in  q
      mode  it  should be relatively short, since it defines
      the maximum amount of time that a message may  sit  in
      the queue.  (See also the MinQueueAge option.)











Sendmail Installation and Operation Guide          SMM:08-35


           RFC  1123  section  5.3.1.1  says that this value
      should be at least 30 minutes (although that  probably
      doesn't make sense if you use ``queue-only'' mode).

           Notice:  the meaning of the interval time depends
      on whether normal queue runners  or  persistent  queue
      runners  are used.  For the former, it is the time be-
      tween subsequent starts of a queue run.  For the  lat-
      ter,  it is the time sendmail waits after a persistent
      queue runner has finished its work to start  the  next
      one.  Hence for persistent queue runners this interval
      should be very low, typically no more  than  two  min-
      utes.

   3.2.  Daemon Mode

           If  you  allow  incoming mail over an IPC connec-
      tion, you should have a daemon running.   This  should
      be  set  by your /etc/rc file using the -bd flag.  The
      -bd flag and the -q flag may be combined in one call:

          /usr/sbin/sendmail -bd -q30m


           An alternative approach  is  to  invoke  sendmail
      from  inetd(8)  (use the -bs -Am flags to ask sendmail
      to speak SMTP on its standard input and output and  to
      run  as MTA).  This works and allows you to wrap send-
      mail in a TCP wrapper program, but may be a bit slower
      since  the configuration file has to be re-read on ev-
      ery message that comes in.  If you do this, you  still
      need to have a sendmail running to flush the queue:

          /usr/sbin/sendmail -q30m


   3.3.  Forcing the Queue

           In  some  cases  you  may find that the queue has
      gotten clogged for some reason.  You can force a queue
      run  using  the -q flag (with no value).  It is enter-
      taining to use the -v flag (verbose) when this is done
      to watch what happens:

          /usr/sbin/sendmail -q -v


           You  can also limit the jobs to those with a par-
      ticular queue identifier, recipient,  sender,  quaran-
      tine  reason,  or  queue  group using one of the queue
      modifiers.  For example, "-qRberkeley"  restricts  the
      queue  run  to  jobs  that  have the string "berkeley"
      somewhere  in  one   of   the   recipient   addresses.










SMM:08-36          Sendmail Installation and Operation Guide


      Similarly,  "-qSstring"  limits  the run to particular
      senders, "-qIstring" limits  it  to  particular  queue
      identifiers,  and  "-qQstring" limits it to particular
      quarantined reasons and only operated  on  quarantined
      queue items, and "-qGstring" limits it to a particular
      queue group.  The named queue group will be  run  even
      if it is set to have 0 runners.  You may also place an
      !  before the I or R or S or Q to indicate  that  jobs
      are  limited to not including a particular queue iden-
      tifier, recipient or sender.  For example,  "-q!Rseat-
      tle" limits the queue run to jobs that do not have the
      string "seattle" somewhere in one of the recipient ad-
      dresses.   Should you need to terminate the queue jobs
      currently active then a SIGTERM to the parent  of  the
      process (or processes) will cleanly stop the jobs.

   3.4.  Debugging

           There  are  a  fairly large number of debug flags
      built into sendmail.  Each debug flag has  a  category
      and  a level.  Higher levels increase the level of de-
      bugging activity; in most cases, this means  to  print
      out  more  information.  The convention is that levels
      greater than nine are "absurd," i.e., they  print  out
      so much information that you wouldn't normally want to
      see them except for debugging that particular piece of
      code.

           You should never run a production sendmail server
      in debug mode.  Many of the debug flags will result in
      debug  output  being sent over the SMTP channel unless
      the option -D is used.  This will  confuse  many  mail
      programs.   However,  for  testing purposes, it can be
      useful when sending mail manually via  telnet  to  the
      port you are using while debugging.

           A  debug  category is either an integer, like 42,
      or a name, like ANSI.  You can specify a range of  nu-
      meric  debug  categories  using the syntax 17-42.  You
      can specify a set of named debug  categories  using  a
      glob  pattern like "sm_trace_*".  At present, only "*"
      and "?"  are supported in these glob patterns.

           Debug flags are set using the -d option; the syn-
      tax is:

          debug-flag:        -d debug-list
          debug-list:        debug-option [ , debug-option ]*
          debug-option:      debug-categories [ . debug-level ]
          debug-categories:  integer | integer - integer | category-pattern
          category-pattern:  [a-zA-Z_*?][a-zA-Z0-9_*?]*
          debug-level:       integer











Sendmail Installation and Operation Guide          SMM:08-37


      where spaces are for reading ease only.  For example,

          -d12               Set category 12 to level 1
          -d12.3             Set category 12 to level 3
          -d3-17             Set categories 3 through 17 to level 1
          -d3-17.4           Set categories 3 through 17 to level 4
          -dANSI             Set category ANSI to level 1
          -dsm_trace_*.3     Set all named categories matching sm_trace_* to level 3

      For  a  complete list of the available debug flags you
      will have to look at the code and the TRACEFLAGS  file
      in  the sendmail distribution (they are too dynamic to
      keep this document up to date).  For a list  of  named
      debug categories in the sendmail binary, use

          ident /usr/sbin/sendmail | grep Debug


   3.5.  Changing the Values of Options

           Options can be overridden using the -o or -O com-
      mand line flags.  For example,

          /usr/sbin/sendmail -oT2m

      sets the T (timeout) option to two  minutes  for  this
      run  only;  the  equivalent line using the long option
      name is

          /usr/sbin/sendmail -OTimeout.queuereturn=2m


           Some options have security  implications.   Send-
      mail  allows  you  to  set these, but relinquishes its
      set-user-ID   or   set-group-ID   permissions   there-
      after[12].

   3.6.  Trying a Different Configuration File

           An alternative configuration file can  be  speci-
      fied using the -C flag; for example,

          /usr/sbin/sendmail -Ctest.cf -oQ/tmp/mqueue

      uses the configuration file test.cf instead of the de-
      fault /etc/mail/sendmail.cf.  If the -C  flag  has  no
____________________
   [12]That  is,  it sets its effective uid to the real uid;
thus, if you are executing as root, as from  root's  crontab
file  or  during  system  startup  the root permissions will
still be honored.












SMM:08-38          Sendmail Installation and Operation Guide


      value it defaults to sendmail.cf in the current direc-
      tory.

           Sendmail gives up  set-user-ID  root  permissions
      (if  it  has been installed set-user-ID root) when you
      use this flag, so it  is  common  to  use  a  publicly
      writable  directory (such as /tmp) as the queue direc-
      tory (QueueDirectory or Q option) while testing.

   3.7.  Logging Traffic

           Many SMTP implementations do not fully  implement
      the  protocol.   For  example,  some personal computer
      based SMTPs do not understand  continuation  lines  in
      reply codes.  These can be very hard to trace.  If you
      suspect such a problem, you can  set  traffic  logging
      using the -X flag.  For example,

          /usr/sbin/sendmail -X /tmp/traffic -bd

      will log all traffic in the file /tmp/traffic.

           This  logs  a lot of data very quickly and should
      NEVER be used during normal operations.  After  start-
      ing  up such a daemon, force the errant implementation
      to send a message to your host.  All  message  traffic
      in  and  out  of sendmail, including the incoming SMTP
      traffic, will be logged in this file.

   3.8.  Testing Configuration Files

           When you build a configuration table, you can  do
      a  certain  amount of testing using the "test mode" of
      sendmail.  For example, you could invoke sendmail as:

          sendmail -bt -Ctest.cf

      which would read the configuration file "test.cf"  and
      enter test mode.  In this mode, you enter lines of the
      form:

          rwset address

      where rwset is the rewriting set you want to  use  and
      address  is an address to apply the set to.  Test mode
      shows you the steps it takes as it  proceeds,  finally
      showing  you the address it ends up with.  You may use
      a comma separated list of rwsets for sequential appli-
      cation of rules to an input.  For example:

          3,1,21,4 monet:bollard

      first    applies    ruleset   three   to   the   input










Sendmail Installation and Operation Guide          SMM:08-39


      "monet:bollard."  Ruleset one is then applied  to  the
      output  of  ruleset three, followed similarly by rule-
      sets twenty-one and four.

           If you need more detail, you  can  also  use  the
      "-d21" flag to turn on more debugging.  For example,

          sendmail -bt -d21.99

      turns on an incredible amount of information; a single
      word address is probably going to  print  out  several
      pages worth of information.

           You  should  be  warned that internally, sendmail
      applies ruleset 3 to all addresses.  In test mode  you
      will  have  to  do  that manually.  For example, older
      versions allowed you to use

          0 bruce@broadcast.sony.com

      This version requires that you use:

          3,0 bruce@broadcast.sony.com


           As of version 8.7, some other syntaxes are avail-
      able in test mode:

      .Dxvalue  defines macro x to have the indicated value.
                This is useful when debugging rules that use
                the $&x syntax.

      .Ccvalue  adds the indicated value to class c.

      =Sruleset dumps the contents of the indicated ruleset.

      -ddebug-spec
                is equivalent to the command-line flag.

      Version 8.9 introduced more features:

      ?         shows a help message.

      =M        display the known mailers.

      $m        print the value of macro m.

      $=c       print the contents of class c.

      /mx host  returns the MX records for `host'.

      /parse address
                parse   address,   returning  the  value  of










SMM:08-40          Sendmail Installation and Operation Guide


                crackaddr, and the parsed address.

      /try mailer addr
                rewrite address into the form it  will  have
                when presented to the indicated mailer.

      /tryflags flags
                set flags used by parsing.  The flags can be
                `H' for Header or `E' for Envelope, and  `S'
                for  Sender or `R' for Recipient.  These can
                be combined, `HR' sets flags for header  re-
                cipients.

      /canon hostname
                try to canonify hostname.

      /map mapname key
                look up `key' in the indicated `mapname'.

      /quit     quit address test mode.

   3.9.  Persistent Host Status Information

           When  HostStatusDirectory is enabled, information
      about the status of hosts is maintained  on  disk  and
      can thus be shared between different instantiations of
      sendmail.  The status of the last connection with each
      remote host may be viewed with the command:

          sendmail -bh

      This information may be flushed with the command:

          sendmail -bH

      Flushing  the  information  prevents new sendmail pro-
      cesses from loading it, but does not prevent  existing
      processes  from using the status information that they
      already have.

4.  TUNING

        There are a number of configuration  parameters  you
   may want to change, depending on the requirements of your
   site.  Most of these are set using an option in the  con-
   figuration   file.    For  example,  the  line  "O  Time-
   out.queuereturn=5d" sets option "Timeout.queuereturn"  to
   the value "5d" (five days).

        Most  of these options have appropriate defaults for
   most sites.  However, sites having very high  mail  loads
   may  find they need to tune them as appropriate for their
   mail load.  In particular,  sites  experiencing  a  large










Sendmail Installation and Operation Guide          SMM:08-41


   number  of small messages, many of which are delivered to
   many recipients, may find that they need  to  adjust  the
   parameters dealing with queue priorities.

        All  versions  of  sendmail  prior to 8.7 had single
   character option names.  As of  8.7,  options  have  long
   (multi-character  names).   Although  old short names are
   still accepted, most new options do not have short equiv-
   alents.

        This section only describes the options you are most
   likely to want to tweak; read section 5 for more details.

   4.1.  Timeouts

           All time intervals are set using a scaled syntax.
      For  example,  "10m"  represents  ten minutes, whereas
      "2h30m" represents two and a half hours.  The full set
      of scales is:

          s   seconds
          m   minutes
          h   hours
          d   days
          w   weeks


      4.1.1.  Queue interval

              The  argument to the -q flag specifies how of-
         ten a sub-daemon will run the queue.  This is typi-
         cally  set to between fifteen minutes and one hour.
         If not set, or set to zero, the queue will  not  be
         run automatically.  RFC 1123 section 5.3.1.1 recom-
         mends that this be at least 30 minutes.  Should you
         need  to  terminate the queue jobs currently active
         then a SIGTERM to the parent  of  the  process  (or
         processes) will cleanly stop the jobs.

      4.1.2.  Read timeouts

              Timeouts all have option names "Timeout.subop-
         tion".  Most of these control SMTP operations.  The
         recognized  suboptions,  their  default values, and
         the minimum values  allowed  by  RFC  2821  section
         4.5.3.2 (or RFC 1123 section 5.3.2) are:

         connect   The  time  to wait for an SMTP connection
                   to open (the connect(2) system call)  [0,
                   unspecified].   If  zero, uses the kernel
                   default.  In no case can this option  ex-
                   tend  the  timeout longer than the kernel
                   provides, but it can shorten it.  This is










SMM:08-42          Sendmail Installation and Operation Guide


                   to get around kernels that provide an ab-
                   surdly long connection timeout  (90  min-
                   utes in one case).

         iconnect  The  same  as  connect, except it applies
                   only to the initial attempt to connect to
                   a  host  for a given message [0, unspeci-
                   fied].  The concept is that  this  should
                   be very short (a few seconds); hosts that
                   are well connected  and  responsive  will
                   thus be serviced immediately.  Hosts that
                   are slow will not hold up other  deliver-
                   ies in the initial delivery attempt.

         aconnect  [0,   unspecified]  The  overall  timeout
                   waiting for all connection for  a  single
                   delivery  attempt  to  succeed.  If 0, no
                   overall limit is applied.   This  can  be
                   used to restrict the total amount of time
                   trying to connect to a long list of  host
                   that  could  accept an e-mail for the re-
                   cipient.  This timeout does not apply  to
                   FallbackMXhost,  i.e., if the time is ex-
                   hausted,  the  FallbackMXhost  is   tried
                   next.

         initial   The  wait  for  the  initial 220 greeting
                   message [5m, 5m].

         helo      The wait for a reply from a HELO or  EHLO
                   command  [5m, unspecified].  This may re-
                   quire a host name lookup, so five minutes
                   is probably a reasonable minimum.

         mail*     The  wait for a reply from a MAIL command
                   [10m, 5m].

         rcpt*     The wait for a reply from a RCPT  command
                   [1h, 5m].  This should be long because it
                   could be pointing at a list that takes  a
                   long time to expand (see below).

         datainit* The  wait for a reply from a DATA command
                   [5m, 2m].

         datablock*#
                   The wait for reading a data  block  (that
                   is,  the body of the message).  [1h, 3m].
                   This should be long because it  also  ap-
                   plies  to  programs piping input to send-
                   mail which have no guarantee  of  prompt-
                   ness.











Sendmail Installation and Operation Guide          SMM:08-43


         datafinal*
                   The  wait for a reply from the dot termi-
                   nating a message.  [1h, 10m].  If this is
                   shorter than the time actually needed for
                   the receiver to deliver the message,  du-
                   plicates will be generated.  This is dis-
                   cussed in RFC 1047.

         rset      The wait for a reply from a RSET  command
                   [5m, unspecified].

         quit      The  wait for a reply from a QUIT command
                   [2m, unspecified].

         misc      The wait for a reply  from  miscellaneous
                   (but short) commands such as NOOP (no-op-
                   eration) and VERB (go into verbose mode).
                   [2m, unspecified].

         command*# In  server SMTP, the time to wait for an-
                   other command.  [1h, 5m].

         ident#    The timeout waiting for  a  reply  to  an
                   IDENT query [5s[13], unspecified].

         lhlo      The wait for a reply to an LMTP LHLO com-
                   mand [2m, unspecified].

         auth      The  timeout  for a reply in an SMTP AUTH
                   dialogue [10m, unspecified].

         starttls  The timeout for a reply to an SMTP START-
                   TLS  command  and  the TLS handshake [1h,
                   unspecified].

         fileopen# The timeout for opening .forward and :in-
                   clude: files [60s, none].

         control#  The timeout for a complete control socket
                   transaction to complete [2m, none].

         hoststatus#
                   How long status information about a  host
                   (e.g.,  host  down) will be cached before
                   it is  considered  stale  [30m,  unspeci-
                   fied].


____________________
   [13]On  some systems the default is zero to turn the pro-
tocol off entirely.












SMM:08-44          Sendmail Installation and Operation Guide


         resolver.retrans#
                   The resolver's retransmission time inter-
                   val (in  seconds)  [varies].   Sets  both
                   Timeout.resolver.retrans.first  and Time-
                   out.resolver.retrans.normal.

         resolver.retrans.first#
                   The resolver's retransmission time inter-
                   val (in seconds) for the first attempt to
                   deliver a message [varies].

         resolver.retrans.normal#
                   The resolver's retransmission time inter-
                   val (in seconds) for all resolver lookups
                   except   the   first   delivery   attempt
                   [varies].

         resolver.retry#
                   The  number  of times to retransmit a re-
                   solver  query.   Sets  both   Timeout.re-
                   solver.retry.first     and    Timeout.re-
                   solver.retry.normal [varies].

         resolver.retry.first#
                   The number of times to retransmit  a  re-
                   solver query for the first attempt to de-
                   liver a message [varies].

         resolver.retry.normal#
                   The number of times to retransmit  a  re-
                   solver query for all resolver lookups
                    except   the   first   delivery  attempt
                   [varies].

         For compatibility with old configuration files,  if
         no  suboption is specified, all the timeouts marked
         with an asterick  (*)  are  set  to  the  indicated
         value.   All but those marked with a pound sign (#)
         apply to client SMTP.

              For example, the lines:

             O Timeout.command=25m
             O Timeout.datablock=3h

         sets the server SMTP command timeout to 25  minutes
         and the input data block timeout to three hours.

      4.1.3.  Message timeouts

              After  sitting in the queue for a few days, an
         undeliverable message will time out.   This  is  to
         insure  that  at  least  the sender is aware of the










Sendmail Installation and Operation Guide          SMM:08-45


         inability to send a message.  The timeout is  typi-
         cally set to five days.  It is sometimes considered
         convenient to also send a warning  message  if  the
         message  is  in  the  queue longer than a few hours
         (assuming you normally have good  connectivity;  if
         your  messages  normally took several hours to send
         you wouldn't want to do this because it wouldn't be
         an  unusual  event).   These timeouts are set using
         the Timeout.queuereturn and  Timeout.queuewarn  op-
         tions  in  the  configuration file (previously both
         were set using the T option).

              If the message is submitted using  the  NOTIFY
         SMTP  extension, warning messages will only be sent
         if NOTIFY=DELAY is specified.  The queuereturn  and
         queuewarn  timeouts can be further qualified with a
         tag based on the Precedence: field in the  message;
         they must be one of "urgent" (indicating a positive
         non-zero precedence), "normal" (indicating  a  zero
         precedence),  or  "non-urgent" (indicating negative
         precedences).  For example, setting "Timeout.queue-
         warn.urgent=1h" sets the warning timeout for urgent
         messages only to  one  hour.   The  default  if  no
         precedence  is  indicated is to set the timeout for
         all precedences.  If the message has a normal  (de-
         fault) precedence and it is a delivery status noti-
         fication (DSN), Timeout.queuereturn.dsn  and  Time-
         out.queuewarn.dsn  can  be used to give an alterna-
         tive warn and return  time  for  DSNs.   The  value
         "now" can be used for -O Timeout.queuereturn to re-
         turn entries immediately during a queue run,  e.g.,
         to bounce messages independent of their time in the
         queue.

              Since these options are global, and since  you
         cannot  know a priori how long another host outside
         your domain will be down, a  five  day  timeout  is
         recommended.   This  allows  a recipient to fix the
         problem even if it occurs at  the  beginning  of  a
         long  weekend.   RFC 1123 section 5.3.1.1 says that
         this parameter should be ``at least 4-5 days''.

              The Timeout.queuewarn value can be piggybacked
         on  the T option by indicating a time after which a
         warning message should be sent;  the  two  timeouts
         are separated by a slash.  For example, the line

             OT5d/4h

         causes email to fail after five days, but a warning
         message will be sent after four hours.  This should
         be  large  enough  that  the message will have been
         tried several times.










SMM:08-46          Sendmail Installation and Operation Guide


   4.2.  Forking During Queue Runs

           By setting the ForkEachJob (Y)  option,  sendmail
      will fork before each individual message while running
      the queue.  This option was used with earlier releases
      to  prevent  sendmail  from consuming large amounts of
      memory.  It should no longer be necessary  with  send-
      mail  8.12.   If  the  ForkEachJob  option is not set,
      sendmail will keep track of hosts that are down during
      a  queue  run,  which can improve performance dramati-
      cally.

           If the ForkEachJob option is set, sendmail cannot
      use connection caching.

   4.3.  Queue Priorities

           Every  message  is assigned a priority when it is
      first instantiated, consisting of the message size (in
      bytes)  offset  by  the message class (which is deter-
      mined from the Precedence:  header)  times  the  "work
      class  factor"  and the number of recipients times the
      "work recipient factor."  The priority is used to  or-
      der  the  queue.  Higher numbers for the priority mean
      that the message will be processed later when  running
      the queue.

           The  message  size is included so that large mes-
      sages are penalized relative to small  messages.   The
      message  class  allows  users  to send "high priority"
      messages by including a "Precedence:" field  in  their
      message; the value of this field is looked up in the P
      lines of the configuration file.  Since the number  of
      recipients  affects  the  amount  of  load  a  message
      presents to the system, this is also included into the
      priority.

           The recipient and class factors can be set in the
      configuration file using the RecipientFactor  (y)  and
      ClassFactor (z) options respectively.  They default to
      30000 (for the recipient factor)  and  1800  (for  the
      class factor).  The initial priority is:

     pri=msgsize-(classxClassFactor)+(nrcptxRecipientFactor)

      (Remember,  higher  values for this parameter actually
      mean that the job will be treated  with  lower  prior-
      ity.)

           The  priority  of a job can also be adjusted each
      time it is processed (that is, each time an attempt is
      made  to deliver it) using the "work time factor," set
      by the RetryFactor (Z) option.  This is added  to  the










Sendmail Installation and Operation Guide          SMM:08-47


      priority,  so  it normally decreases the precedence of
      the job, on the grounds that  jobs  that  have  failed
      many times will tend to fail again in the future.  The
      RetryFactor option defaults to 90000.

   4.4.  Load Limiting

           Sendmail can be asked to queue (but not  deliver)
      mail  if  the  system load average gets too high using
      the QueueLA (x) option.  When the load average exceeds
      the  value of the QueueLA option, the delivery mode is
      set to q (queue only) if the  QueueFactor  (q)  option
      divided  by the difference in the current load average
      and the QueueLA option plus one is less than the  pri-
      ority of the message -- that is, the message is queued
      iff:

                        pri>LQueueFactor_

      The QueueFactor option defaults  to  600000,  so  each
      point  of load average is worth 600000 priority points
      (as described above).

           For drastic cases, the RefuseLA  (X)  option  de-
      fines  a load average at which sendmail will refuse to
      accept network connections.  Locally  generated  mail,
      i.e.,  mail which is not submitted via SMTP (including
      incoming UUCP mail), is still accepted.   Notice  that
      the  MSP  submits  mail to the MTA via SMTP, and hence
      mail will be queued in the  client  queue  in  such  a
      case.   Therefore  it  is  necessary to run the client
      mail queue periodically.

   4.5.  Resource Limits

           Sendmail has several parameters  to  control  re-
      source usage.  Besides those mentioned in the previous
      section, there are at least MaxDaemonChildren, Connec-
      tionRateThrottle,    MaxQueueChildren,   and   MaxRun-
      nersPerQueue.  The latter  two  limit  the  number  of
      sendmail  processes  that operate on the queue.  These
      are discussed in the section  ``Queue  Group  Declara-
      tion''.   The former two can be used to limit the num-
      ber of incoming connections.  Their appropriate values
      depend  on the host operating system and the hardware,
      e.g., amount of memory.  In many situations  it  might
      be  useful  to  set limits to prevent to have too many
      sendmail  processes,  however,  these  limits  can  be
      abused to mount a denial of service attack.  For exam-
      ple, if MaxDaemonChildren=10 then an attacker needs to
      open  only  10 SMTP sessions to the server, leave them
      idle for most of the time,  and  no  more  connections
      will  be  accepted.   If  this  option is set then the










SMM:08-48          Sendmail Installation and Operation Guide


      timeouts used in a SMTP session should be lowered from
      their default values to their minimum values as speci-
      fied in RFC 2821 and listed in section 4.1.2.

   4.6.  Measures against Denial of Service Attacks

           Sendmail has some built-in measures against  sim-
      ple  denial of service (DoS) attacks.  The SMTP server
      by default slows down if too many bad commands are is-
      sued or if some commands are repeated too often within
      a session.  Details can be found in  the  source  file
      sendmail/srvrsmtp.c  by  looking for the macro defini-
      tions of MAXBADCOMMANDS, MAXNOOPCOMMANDS,  MAXHELOCOM-
      MANDS,  MAXVRFYCOMMANDS,  and  MAXETRNCOMMANDS.  If an
      SMTP command is issued more often than the correspond-
      ing MAXcmdCOMMANDS value, then the response is delayed
      exponentially, starting with a sleep time of one  sec-
      ond,  up  to  a maximum of four minutes (as defined by
      MAXTIMEOUT).  If the option MaxDaemonChildren  is  set
      to  a  value greater than zero, then this could make a
      DoS attack even worse since it keeps a connection open
      longer than necessary.  Therefore a connection is ter-
      minated with a 421 SMTP reply code if  the  number  of
      commands  exceeds  the  limit  by  a factor of two and
      MAXBADCOMMANDS is set to a  value  greater  than  zero
      (the default is 25).

   4.7.  Delivery Mode

           There  are  a number of delivery modes that send-
      mail can operate in, set by the DeliveryMode (d)  con-
      figuration  option.   These  modes specify how quickly
      mail will be delivered.  Legal modes are:

          i   deliver interactively (synchronously)
          b   deliver in background (asynchronously)
          q   queue only (don't deliver)
          d   defer delivery attempts (don't deliver)

      There are tradeoffs.  Mode "i" gives  the  sender  the
      quickest  feedback, but may slow down some mailers and
      is hardly ever necessary.  Mode "b" delivers  promptly
      but can cause large numbers of processes if you have a
      mailer that takes a long time to  deliver  a  message.
      Mode "q" minimizes the load on your machine, but means
      that delivery may be delayed for up to the  queue  in-
      terval.  Mode "d" is identical to mode "q" except that
      it also prevents lookups in maps including the -D flag
      from working during the initial queue phase; it is in-
      tended for ``dial on demand'' sites where DNS  lookups
      might  cost  real  money.   Some simple error messages
      (e.g., host unknown during the SMTP protocol) will  be
      delayed  using  this  mode.   Mode  "b"  is  the usual










Sendmail Installation and Operation Guide          SMM:08-49


      default.

           If you run in mode "q" (queue only), "d" (defer),
      or  "b"  (deliver in background) sendmail will not ex-
      pand aliases and follow .forward  files  upon  initial
      receipt  of  the mail.  This speeds up the response to
      RCPT commands.  Mode "i" should not  be  used  by  the
      SMTP server.

   4.8.  Log Level

           The  level  of  logging  can be set for sendmail.
      The default using a standard configuration is level 9.
      The  levels  are  approximately  as  follows (some log
      types are using different level depending  on  various
      factors):

      0    Minimal logging.

      1    Serious  system  failures  and potential security
           problems.

      2    Lost communications (network problems) and proto-
           col failures.

      3    Other   serious  failures,  malformed  addresses,
           transient  forward/include   errors,   connection
           timeouts.

      4    Minor failures, out of date alias databases, con-
           nection rejections via check_ rulesets.

      5    Message collection statistics.

      6    Creation of error messages, VRFY  and  EXPN  com-
           mands.

      7    Delivery failures (host or user unknown, etc.).

      8    Successful  deliveries  and  alias  database  re-
           builds.

      9    Messages being deferred  (due  to  a  host  being
           down, etc.).

      10   Database  expansion  (alias,  forward, and userdb
           lookups) and authentication information.

      11   NIS errors and end of job processing.

      12   Logs all SMTP connections.












SMM:08-50          Sendmail Installation and Operation Guide


      13   Log bad user shells, files with improper  permis-
           sions, and other questionable situations.

      14   Logs refused connections.

      15   Log all incoming SMTP commands.

      20   Logs  attempts  to run locked queue files.  These
           are not errors, but can be useful to note if your
           queue appears to be clogged.

      30   Lost  locks  (only  if  using  lockf  instead  of
           flock).

      Additionally, values above 64  are  reserved  for  ex-
      tremely  verbose  debugging  output.   No  normal site
      would ever set these.

   4.9.  File Modes

           The modes used for files depend on what function-
      ality  you want and the level of security you require.
      In many cases sendmail does careful  checking  of  the
      modes  of  files  and  directories to avoid accidental
      compromise; if you want to make it  possible  to  have
      group-writable  support  files you may need to use the
      DontBlameSendmail option to turn  off  some  of  these
      checks.

      4.9.1.  To suid or not to suid?

              Sendmail is no longer installed set-user-ID to
         root.  sendmail/SECURITY explains how to  configure
         and  install  sendmail  without set-user-ID to root
         but set-group-ID which is the default configuration
         starting with 8.12.

              The  daemon usually runs as root, unless other
         measures are taken.  At the point where sendmail is
         about  to exec(2) a mailer, it checks to see if the
         userid is zero (root); if so, it resets the  userid
         and  groupid  to a default (set by the U= equate in
         the mailer line; if that is not set,  the  Default-
         User  option  is  used).  This can be overridden by
         setting the S flag to the mailer for  mailers  that
         are  trusted  and must be called as root.  However,
         this will cause mail  processing  to  be  accounted
         (using sa(8)) to root rather than to the user send-
         ing the mail.

              A middle ground is to set  the  RunAsUser  op-
         tion.  This causes sendmail to become the indicated
         user as soon  as  it  has  done  the  startup  that










Sendmail Installation and Operation Guide          SMM:08-51


         requires  root  privileges  (primarily, opening the
         SMTP socket).  If you use RunAsUser, the queue  di-
         rectory   (normally  /var/spool/mqueue)  should  be
         owned by that user, and  all  files  and  databases
         (including  user  .forward files, alias files, :in-
         clude: files, and external databases) must be read-
         able  by  that user.  Also, since sendmail will not
         be able to change its uid, delivery to programs  or
         files  will  be  marked as unsafe, e.g., undeliver-
         able, in .forward, aliases,  and  :include:  files.
         Administrators  can  override  this  by setting the
         DontBlameSendmail option to  the  setting  NonRoot-
         SafeAddr.   RunAsUser  is  probably best suited for
         firewall configurations  that  don't  have  regular
         user  logins.   If  the  option is used on a system
         which performs local delivery, then the  local  de-
         livery  agent  must  have  the  proper  permissions
         (i.e., usually set-user-ID root) since it  will  be
         invoked by the RunAsUser, not by root.

      4.9.2.  Turning off security checks

              Sendmail is very particular about the modes of
         files that it reads or writes.  For example, by de-
         fault  it  will  refuse to read most files that are
         group writable on the grounds that they might  have
         been tampered with by someone other than the owner;
         it will even refuse to read files in group writable
         directories.   Also, sendmail will refuse to create
         a new aliases database in an unsafe directory.  You
         can  get around this by manually creating the data-
         base file as a trusted user ahead of time and  then
         rebuilding the aliases database with newaliases.

              If  you are quite sure that your configuration
         is safe and you want sendmail to avoid these  secu-
         rity  checks, you can turn off certain checks using
         the DontBlameSendmail option.   This  option  takes
         one  or more names that disable checks.  In the de-
         scriptions that follow, "unsafe directory" means  a
         directory that is writable by anyone other than the
         owner.  The values are:

         Safe No special handling.

         AssumeSafeChown
              Assume that  the  chown  system  call  is  re-
              stricted to root.  Since some versions of UNIX
              permit regular users to give away their  files
              to  other  users on some filesystems, sendmail
              often cannot assume that a given file was cre-
              ated  by the owner, particularly when it is in
              a writable directory.  You can set  this  flag










SMM:08-52          Sendmail Installation and Operation Guide


              if  you  know that file giveaway is restricted
              on your system.

         ClassFileInUnsafeDirPath
              When reading class files (using the F line  in
              the  configuration file), allow files that are
              in unsafe directories.

         DontWarnForwardFileInUnsafeDirPath
              Prevent logging of unsafe directory path warn-
              ings for non-existent forward files.

         ErrorHeaderInUnsafeDirPath
              Allow the file named in the ErrorHeader option
              to be in an unsafe directory.

         FileDeliveryToHardLink
              Allow delivery to files that are hard links.

         FileDeliveryToSymLink
              Allow delivery  to  files  that  are  symbolic
              links.

         ForwardFileInGroupWritableDirPath
              Allow  .forward files in group writable direc-
              tories.

         ForwardFileInUnsafeDirPath
              Allow .forward files in unsafe directories.

         ForwardFileInUnsafeDirPathSafe
              Allow a .forward file that is in an unsafe di-
              rectory  to  include references to program and
              files.

         GroupReadableKeyFile
              Accept a group-readable key file for STARTTLS.

         GroupReadableSASLDBFile
              Accept a group-readable  Cyrus  SASL  password
              file.

         GroupReadableDefaultAuthInfoFile
              Accept  a  group-readable DefaultAuthInfo file
              for SASL.

         GroupWritableAliasFile
              Allow group-writable alias files.

         GroupWritableDirPathSafe
              Change the definition of "unsafe directory" to
              consider   group-writable  directories  to  be
              safe.  World-writable directories  are  always










Sendmail Installation and Operation Guide          SMM:08-53


              unsafe.

         GroupWritableForwardFile
              Allow group writable .forward files.

         GroupWritableForwardFileSafe
              Accept  group-writable  .forward files as safe
              for program and file delivery.

         GroupWritableIncludeFile
              Allow group writable :include: files.

         GroupWritableIncludeFileSafe
              Accept group-writable :include: files as  safe
              for program and file delivery.

         GroupWritableSASLDBFile
              Accept  a  group-writable  Cyrus SASL password
              file.

         HelpFileInUnsafeDirPath
              Allow the file named in the HelpFile option to
              be in an unsafe directory.

         IncludeFileInGroupWritableDirPath
              Allow :include: files in group writable direc-
              tories.

         IncludeFileInUnsafeDirPath
              Allow :include: files in unsafe directories.

         IncludeFileInUnsafeDirPathSafe
              Allow a :include: file that is  in  an  unsafe
              directory to include references to program and
              files.

         InsufficientEntropy
              Try to use  STARTTLS  even  if  the  PRNG  for
              OpenSSL is not properly seeded despite the se-
              curity problems.

         LinkedAliasFileInWritableDir
              Allow an alias  file  that  is  a  link  in  a
              writable directory.

         LinkedClassFileInWritableDir
              Allow  class  files that are links in writable
              directories.

         LinkedForwardFileInWritableDir
              Allow  .forward  files  that  are   links   in
              writable directories.











SMM:08-54          Sendmail Installation and Operation Guide


         LinkedIncludeFileInWritableDir
              Allow   :include:  files  that  are  links  in
              writable directories.

         LinkedMapInWritableDir
              Allow map files that are links in writable di-
              rectories.    This   includes  alias  database
              files.

         LinkedServiceSwitchFileInWritableDir
              Allow the service switch file  to  be  a  link
              even if the directory is writable.

         MapInUnsafeDirPath
              Allow  maps (e.g., hash, btree, and dbm files)
              in unsafe directories.   This  includes  alias
              database files.

         NonRootSafeAddr
              Do not mark file and program deliveries as un-
              safe if sendmail  is  not  running  with  root
              privileges.

         RunProgramInUnsafeDirPath
              Run  programs that are in writable directories
              without logging a warning.

         RunWritableProgram
              Run programs that are group- or world-writable
              without logging a warning.

         TrustStickyBit
              Allow  group  or world writable directories if
              the sticky bit is set on  the  directory.   Do
              not set this on systems which do not honor the
              sticky bit on directories.

         WorldWritableAliasFile
              Accept world-writable alias files.

         WorldWritableForwardfile
              Allow world writable .forward files.

         WorldWritableIncludefile
              Allow world writable :include: files.

         WriteMapToHardLink
              Allow writes to maps that are hard links.

         WriteMapToSymLink
              Allow writes to maps that are symbolic links.












Sendmail Installation and Operation Guide          SMM:08-55


         WriteStatsToHardLink
              Allow the status file to be a hard link.

         WriteStatsToSymLink
              Allow the status file to be a symbolic link.

   4.10.  Connection Caching

           When processing the queue, sendmail will  try  to
      keep  the  last  few  open  connections  open to avoid
      startup and shutdown costs.  This only applies to  IPC
      and LPC connections.

           When  trying  to  open  a connection the cache is
      first searched.  If an open connection is found, it is
      probed  to see if it is still active by sending a RSET
      command.  It is not an error if this  fails;  instead,
      the connection is closed and reopened.

           Two parameters control the connection cache.  The
      ConnectionCacheSize (k) option defines the  number  of
      simultaneous  open connections that will be permitted.
      If it is set to zero, connections will  be  closed  as
      quickly as possible.  The default is one.  This should
      be set as appropriate for your system  size;  it  will
      limit  the  amount  of  system resources that sendmail
      will use during queue runs.   Never  set  this  higher
      than 4.

           The  ConnectionCacheTimeout  (K) option specifies
      the maximum time that any cached  connection  will  be
      permitted  to  idle.   When the idle time exceeds this
      value the connection is closed.  This number should be
      small (under ten minutes) to prevent you from grabbing
      too many resources from other hosts.  The  default  is
      five minutes.

   4.11.  Name Server Access

           Control  of  host  address  lookups is set by the
      hosts service entry in your service switch  file.   If
      you  are  on a system that has built-in service switch
      support (e.g., Ultrix, Solaris,  or  DEC  OSF/1)  then
      your  system  is probably configured properly already.
      Otherwise,   sendmail   will    consult    the    file
      /etc/mail/service.switch,  which  should  be  created.
      Sendmail only uses two entries: hosts and aliases, al-
      though system routines may use other services (notably
      the passwd service for user  name  lookups  by  getpw-
      name).

           However, some systems (such as SunOS 4.X) will do
      DNS lookups regardless of the setting of  the  service










SMM:08-56          Sendmail Installation and Operation Guide


      switch entry.  In particular, the system routine geth-
      ostbyname(3) is used to look up host names,  and  many
      vendor  versions try some combination of DNS, NIS, and
      file lookup in /etc/hosts without consulting a service
      switch.  Sendmail makes no attempt to work around this
      problem, and the DNS lookup will be done  anyway.   If
      you  do  not have a nameserver configured at all, such
      as at a UUCP-only site, sendmail will get  a  "connec-
      tion  refused" message when it tries to connect to the
      name server.  If the hosts switch entry has  the  ser-
      vice "dns" listed somewhere in the list, sendmail will
      interpret this to mean a temporary  failure  and  will
      queue the mail for later processing; otherwise, it ig-
      nores the name server data.

           The same technique is used to decide  whether  to
      do  MX lookups.  If you want MX support, you must have
      "dns" listed as a service in the hosts switch entry.

           The ResolverOptions  (I)  option  allows  you  to
      tweak  name  server options.  The command line takes a
      series of flags as documented in resolver(3) (with the
      leading  "RES_"  deleted).  Each can be preceded by an
      optional `+' or `-'.  For example, the line

          O ResolverOptions=+AAONLY -DNSRCH

      turns on  the  AAONLY  (accept  authoritative  answers
      only)  and  turns  off  the  DNSRCH (search the domain
      path)  options.   Most  resolver   libraries   default
      DNSRCH,  DEFNAMES, and RECURSE flags on and all others
      off.  If NETINET6 is enabled, most  libraries  default
      to  USE_INET6 as well.  You can also include "HasWild-
      cardMX" to specify that there is a wildcard MX  record
      matching  your domain; this turns off MX matching when
      canonifying names, which  can  lead  to  inappropriate
      canonifications.    Use   "WorkAroundBrokenAAAA"  when
      faced with a broken nameserver that  returns  SERVFAIL
      (a  temporary failure) on T_AAAA (IPv6) lookups during
      hostname canonification.  Notice: it might  be  neces-
      sary  to  apply  the same (or similar) options to sub-
      mit.cf too.

           Version level 1 configurations (see  the  section
      about ``Configuration Version Level'') turn DNSRCH and
      DEFNAMES off when doing delivery  lookups,  but  leave
      them  on  everywhere  else.  Version 8 of sendmail ig-
      nores them when doing canonification lookups (that is,
      when using $[ ... $]), and always does the search.  If
      you don't want to do automatic name  extension,  don't
      call $[ ... $].












Sendmail Installation and Operation Guide          SMM:08-57


           The  search rules for $[ ... $] are somewhat dif-
      ferent than usual.  If the name being looked up has at
      least  one  dot,  it  always tries the unmodified name
      first.  If that fails, it  tries  the  reduced  search
      path,  and  lastly tries the unmodified name (but only
      for names without a dot, since names with a  dot  have
      already  been  tried).   This  allows  names  such  as
      ``utc.CS'' to match the site in Czechoslovakia  rather
      than  the  site in your local Computer Science depart-
      ment.  It also prefers A and  CNAME  records  over  MX
      records  -- that is, if it finds an MX record it makes
      note of it, but keeps looking.  This way, if you  have
      a wildcard MX record matching your domain, it will not
      assume that all names match.

           To completely turn off all name server access  on
      systems  without service switch support (such as SunOS
      4.X) you will have to  recompile  with  -DNAMED_BIND=0
      and  remove  -lresolv from the list of libraries to be
      searched when linking.

   4.12.  Moving the Per-User Forward Files

           Some sites mount each user's home directory  from
      a  local  disk on their workstation, so that local ac-
      cess is fast.  However, the result  is  that  .forward
      file  lookups from a central mail server are slow.  In
      some cases, mail can even be delivered on machines in-
      appropriately  because  of  a  file server being down.
      The performance can be especially bad if you  run  the
      automounter.

           The  ForwardPath  (J)  option allows you to set a
      path of forward files.  For example, the  config  file
      line

          O ForwardPath=/var/forward/$u:$z/.forward.$w

      would  first look for a file with the same name as the
      user's login in /var/forward; if that is not found (or
      is  inaccessible) the file ``.forward.machinename'' in
      the user's home directory is searched.  A  truly  per-
      verse  site  could  also search by sender by using $r,
      $s, or $f.

           If you create a directory such  as  /var/forward,
      it should be mode 1777 (that is, the sticky bit should
      be set).  Users should create  the  files  mode  0644.
      Note  that you must use the ForwardFileInUnsafeDirPath
      and  ForwardFileInUnsafeDirPathSafe  flags  with   the
      DontBlameSendmail  option  to allow forward files in a
      world writable directory.  This might also be used  as
      a denial of service attack (users could create forward










SMM:08-58          Sendmail Installation and Operation Guide


      files for other users); a better approach might be  to
      create  /var/forward  mode 0755 and create empty files
      for each user, owned by that user, mode 0644.  If  you
      do  this,  you don't have to set the DontBlameSendmail
      options indicated above.

   4.13.  Free Space

           On systems that have one of the system  calls  in
      the  statfs(2)  family  (including statvfs and ustat),
      you can specify a minimum number of free blocks on the
      queue  filesystem  using the MinFreeBlocks (b) option.
      If there are fewer than the indicated number of blocks
      free  on  the filesystem on which the queue is mounted
      the SMTP server will reject mail with  the  452  error
      code.   This  invites  the  SMTP  client  to try again
      later.

           Beware of setting this option too  high;  it  can
      cause  rejection of email when that mail would be pro-
      cessed without difficulty.

   4.14.  Maximum Message Size

           To avoid overflowing your  system  with  a  large
      message,  the  MaxMessageSize option can be set to set
      an absolute limit on the  size  of  any  one  message.
      This  will  be  advertised  in  the ESMTP dialogue and
      checked during message collection.

   4.15.  Privacy Flags

           The PrivacyOptions (p) option allows you  to  set
      certain  ``privacy''  flags.   Actually,  many of them
      don't give you any extra privacy, rather just  insist-
      ing  that client SMTP servers use the HELO command be-
      fore using certain commands or adding extra headers to
      indicate possible spoof attempts.

           The  option takes a series of flag names; the fi-
      nal privacy is the inclusive or of those  flags.   For
      example:

          O PrivacyOptions=needmailhelo, noexpn

      insists that the HELO or EHLO command be used before a
      MAIL command is accepted and disables  the  EXPN  com-
      mand.

           The flags are detailed in section 5.6.













Sendmail Installation and Operation Guide          SMM:08-59


   4.16.  Send to Me Too

           Beginning with version 8.10, sendmail includes by
      default the (envelope) sender in any list  expansions.
      For  example,  if "matt" sends to a list that contains
      "matt" as one of the members he will get a copy of the
      message.   If the MeToo option is set to FALSE (in the
      configuration file or via the command line), this  be-
      havior  is changed, i.e., the (envelope) sender is ex-
      cluded in list expansions.

5.  THE WHOLE SCOOP ON THE CONFIGURATION FILE

        This section describes the configuration file in de-
   tail.

        There is one point that should be made clear immedi-
   ately: the syntax of the configuration file  is  designed
   to  be reasonably easy to parse, since this is done every
   time sendmail starts up, rather than easy for a human  to
   read  or  write.  The configuration file should be gener-
   ated via the method described in cf/README, it should not
   be  edited  directly  unless someone is familiar with the
   internals of the syntax described here and it is not pos-
   sible  to  achieve  the  desired  result  via the default
   method.

        The configuration file is organized as a  series  of
   lines,  each  of  which  begins  with  a single character
   defining the semantics for the rest of the  line.   Lines
   beginning  with  a  space or a tab are continuation lines
   (although the semantics are  not  well  defined  in  many
   places).   Blank  lines  and lines beginning with a sharp
   symbol (`#') are comments.

   5.1.  R and S -- Rewriting Rules

           The core of address  parsing  are  the  rewriting
      rules.  These are an ordered production system.  Send-
      mail scans through the set of rewriting rules  looking
      for  a  match on the left hand side (LHS) of the rule.
      When a rule matches, the address is  replaced  by  the
      right hand side (RHS) of the rule.

           There  are several sets of rewriting rules.  Some
      of the rewriting sets are  used  internally  and  must
      have  specific semantics.  Other rewriting sets do not
      have specifically assigned semantics, and may be  ref-
      erenced  by the mailer definitions or by other rewrit-
      ing sets.

           The syntax of these two commands are:











SMM:08-60          Sendmail Installation and Operation Guide


          Sn

      Sets the current ruleset being collected to n.  If you
      begin  a  ruleset more than once it appends to the old
      definition.

          Rlhs rhs comments

      The fields must be separated by at least one tab char-
      acter;  there  may  be  embedded spaces in the fields.
      The lhs is a pattern that is applied to the input.  If
      it  matches,  the  input is rewritten to the rhs.  The
      comments are ignored.

           Macro expansions of the  form  $x  are  performed
      when  the configuration file is read.  A literal $ can
      be included using $$.  Expansions of the form $&x  are
      performed  at  run  time using a somewhat less general
      algorithm.  This is intended only for referencing  in-
      ternally defined macros such as $h that are changed at
      runtime.

      5.1.1.  The left hand side

              The left hand side of rewriting rules contains
         a  pattern.   Normal  words  are simply matched di-
         rectly.  Metasyntax is introduced  using  a  dollar
         sign.  The metasymbols are:

             $*   Match zero or more tokens
             $+   Match one or more tokens
             $-   Match exactly one token
             $=x  Match any phrase in class x
             $~x  Match any word not in class x

         If  any  of  these  match, they are assigned to the
         symbol $n for replacement on the right  hand  side,
         where  n  is the index in the LHS.  For example, if
         the LHS:

             $-:$+

         is applied to the input:

             UCBARPA:eric

         the rule will match, and the values passed  to  the
         RHS will be:

             $1  UCBARPA
             $2  eric












Sendmail Installation and Operation Guide          SMM:08-61


              Additionally,  the LHS can include $@ to match
         zero tokens.  This is not bound to a $n on the RHS,
         and  is  normally only used when it stands alone in
         order to match the null input.

      5.1.2.  The right hand side

              When the left hand side of  a  rewriting  rule
         matches,  the  input is deleted and replaced by the
         right hand side.  Tokens are copied  directly  from
         the  RHS  unless  they  begin  with  a dollar sign.
         Metasymbols are:

             $n         Substitute indefinite token n from LHS
             $[name$]   Canonicalize name
             $(map key $@arguments $:default $)
                        Generalized keyed mapping function
             $>n        "Call" ruleset n
             $#mailer   Resolve to mailer
             $@host     Specify host
             $:user     Specify user


              The $n syntax  substitutes  the  corresponding
         value  from  a  $+,  $-, $*, $=, or $~ match on the
         LHS.  It may be used anywhere.

              A host name enclosed  between  $[  and  $]  is
         looked  up  in the host database(s) and replaced by
         the  canonical  name[14].   For  example, "$[ftp$]"
         might     become     "ftp.CS.Berkeley.EDU"      and
         "$[[128.32.130.2]$]"     would     become     "van-
         gogh.CS.Berkeley.EDU."  Sendmail recognizes its nu-
         meric  IP  address  without calling the name server
         and replaces it with its canonical name.

              The $( ...  $) syntax is a more  general  form
         of  lookup;  it  uses a named map instead of an im-
         plicit map.  If no lookup is found,  the  indicated
         default is inserted; if no default is specified and
         no lookup matches, the  value  is  left  unchanged.
         The  arguments  are  passed to the map for possible
         use.

              The $>n syntax causes  the  remainder  of  the
         line  to be substituted as usual and then passed as
         the argument to ruleset  n.   The  final  value  of
         ruleset  n  then  becomes the substitution for this
____________________
   [14]This is  actually  completely  equivalent  to  $(host
hostname$).  In particular, a $: default can be used.












SMM:08-62          Sendmail Installation and Operation Guide


         rule.  The $> syntax expands everything  after  the
         ruleset  name  to the end of the replacement string
         and then passes that as the initial  input  to  the
         ruleset.   Recursive  calls are allowed.  For exam-
         ple,

             $>0 $>3 $1

         expands $1, passes that  to  ruleset  3,  and  then
         passes the result of ruleset 3 to ruleset 0.

              The  $#  syntax should only be used in ruleset
         zero, a subroutine of  ruleset  zero,  or  rulesets
         that   return  decisions  (e.g.,  check_rcpt).   It
         causes evaluation of the ruleset to terminate imme-
         diately,  and  signals to sendmail that the address
         has completely resolved.  The complete  syntax  for
         ruleset 0 is:

             $#mailer $@host $:user

         This  specifies  the  {mailer,  host, user} 3-tuple
         (triple) necessary to direct the mailer.  Note: the
         third element ( user ) is often also called address
         part.  If the mailer is local the host part may  be
         omitted[15].  The mailer must be a single word, but
         the host and user may be multi-part.  If the mailer
         is the built-in IPC mailer, the host may be a colon
         (or  comma) separated list of hosts.  Each is sepa-
         rately MX expanded and the results are concatenated
         to make (essentially) one long MX list.  Hosts sep-
         arated by a comma have the same MX preference,  and
         for  each colon separated host the MX preference is
         increased.  The user  is  later  rewritten  by  the
         mailer-specific envelope rewriting set and assigned
         to the $u macro.  As a special case, if the  mailer
         specified  has the F=@ flag specified and the first
         character of the  $:  value  is  "@",  the  "@"  is
         stripped  off, and a flag is set in the address de-
         scriptor that causes sendmail to not do  ruleset  5
         processing.

              Normally, a rule that matches is retried, that
         is, the rule loops until it fails.  A RHS may  also
         be  preceded  by a $@ or a $: to change this behav-
         ior.  A $@ prefix causes the ruleset to return with
____________________
   [15]You  may want to use it for special "per user" exten-
sions.  For example, in the address  "jgm+foo@CMU.EDU";  the
"+foo"  part  is not part of the user name, and is passed to
the local mailer for local use.












Sendmail Installation and Operation Guide          SMM:08-63


         the remainder of the RHS as the value.  A $: prefix
         causes the rule to terminate immediately,  but  the
         ruleset to continue; this can be used to avoid con-
         tinued  application  of  a  rule.   The  prefix  is
         stripped before continuing.

              The  $@ and $: prefixes may precede a $> spec;
         for example:

             R$+     $: $>7 $1

         matches anything, passes that to ruleset seven, and
         continues; the $: is necessary to avoid an infinite
         loop.

              Substitution occurs in  the  order  described,
         that  is,  parameters from the LHS are substituted,
         hostnames  are  canonicalized,  "subroutines"   are
         called, and finally $#, $@, and $: are processed.

      5.1.3.  Semantics of rewriting rule sets

              There  are  six  rewriting sets that have spe-
         cific semantics.  Five of these are related as  de-
         picted by figure 1.

              Ruleset  three  should  turn  the address into
         "canonical form."  This form should have the  basic
         syntax:


____________________________________________________________

                    +---+
                 -->| 0 |-->resolved address
                /   +---+
               /            +---+   +---+
              /        ---->| 1 |-->| S |--
       +---+ / +---+  /     +---+   +---+  \    +---+
addr-->| 3 |-->| D |--                      --->| 4 |-->msg
       +---+   +---+  \     +---+   +---+  /    +---+
                        --->| 2 |-->| R |--
                            +---+   +---+

            Figure 1 -- Rewriting set semantics
          D -- sender domain addition
          S -- mailer-specific sender rewriting
          R -- mailer-specific recipient rewriting
____________________________________________________________














SMM:08-64          Sendmail Installation and Operation Guide


             local-part@host-domain-spec

         Ruleset  three  is applied by sendmail before doing
         anything with any address.

              If no "@" sign is specified, then the host-do-
         main-spec  may  be  appended  (box "D" in Figure 1)
         from the sender address (if the C flag  is  set  in
         the  mailer definition corresponding to the sending
         mailer).

              Ruleset zero is applied after ruleset three to
         addresses that are going to actually specify recip-
         ients.  It must resolve to  a  {mailer,  host,  ad-
         dress}  triple.   The mailer must be defined in the
         mailer definitions  from  the  configuration  file.
         The  host  is  defined into the $h macro for use in
         the argv expansion of the  specified  mailer.   No-
         tice:  since  the  envelope  sender address will be
         used if a  delivery  status  notification  must  be
         send,  i.e., it may specify a recipient, it is also
         run through ruleset zero.  If ruleset zero  returns
         a  temporary  error  4xy then delivery is deferred.
         This can be used to temporarily  disable  delivery,
         e.g., based on the time of the day or other varying
         parameters.  It should not be used to quarantine e-
         mails.

              Rulesets one and two are applied to all sender
         and recipient addresses respectively.  They are ap-
         plied  before any specification in the mailer defi-
         nition.  They must never resolve.

              Ruleset four is applied to  all  addresses  in
         the message.  It is typically used to translate in-
         ternal to external form.

              In addition, ruleset 5 is applied to all local
         addresses  (specifically,  those  that resolve to a
         mailer with the `F=5' flag set) that  do  not  have
         aliases.   This allows a last minute hook for local
         names.

      5.1.4.  Ruleset hooks

              A few extra rulesets are  defined  as  "hooks"
         that  can be defined to get special features.  They
         are all named rulesets.  The  "check_*"  forms  all
         give  accept/reject  status; falling off the end or
         returning normally is an accept, and  resolving  to
         $#error is a reject or quarantine.  Quarantining is
         chosen by specifying quarantine in the second  part
         of the mailer triplet:










Sendmail Installation and Operation Guide          SMM:08-65


             $#error $@ quarantine $: Reason for quarantine

         Many  of  these  can  also  resolve  to the special
         mailer name $#discard; this accepts the message  as
         though  it  were  successful  but  then discards it
         without delivery.  Note, this mailer cannot be cho-
         sen  as  a mailer in ruleset 0.  Note also that all
         "check_*" rulesets  have  to  deal  with  temporary
         failures,  especially  for map lookups, themselves,
         i.e., they should return a temporary error code  or
         at  least  they  should  make  a proper decision in
         those cases.

         5.1.4.1.  check_relay

                 The check_relay ruleset is called  after  a
            connection is accepted by the daemon.  It is not
            called when sendmail is started  using  the  -bs
            option.  It is passed

                client.host.name $| client.host.address

            where  $|  is a metacharacter separating the two
            parts.  This ruleset can reject connections from
            various locations.  Note that it only checks the
            connecting SMTP client IP address and  hostname.
            It does not check for third party message relay-
            ing.  The  check_rcpt  ruleset  discussed  below
            usually does third party message relay checking.

         5.1.4.2.  check_mail

                 The  check_mail  ruleset is passed the user
            name parameter of the SMTP MAIL command.  It can
            accept or reject the address.

         5.1.4.3.  check_rcpt

                 The  check_rcpt  ruleset is passed the user
            name parameter of the SMTP RCPT command.  It can
            accept or reject the address.

         5.1.4.4.  check_data

                 The  check_data ruleset is called after the
            SMTP DATA command, its parameter is  the  number
            of recipients.  It can accept or reject the com-
            mand.

         5.1.4.5.  check_other

                 The check_other ruleset is invoked for  all
            unknown  SMTP commands and for commands which do










SMM:08-66          Sendmail Installation and Operation Guide


            not have specific rulesets, e.g., NOOP and VERB.
            Internal  checks, e.g., those explained in "Mea-
            sures against Denial of  Service  Attacks",  are
            performed first.  The ruleset is passed

                entire-SMTP-command $| SMTP-reply-first-digit

            where  $|  is a metacharacter separating the two
            parts.  For example,

                VERB $| 2

            reflects receiving the "VERB" SMTP  command  and
            the intent to return a "2XX" SMTP success reply.
            Alternatively,

                JUNK TYPE=I $| 5

            reflects receiving  the  unknown  "JUNK  TYPE=I"
            SMTP  command  and  the intent to return a "5XX"
            SMTP failure reply.  If the ruleset returns  the
            SMTP reply code 421:

                $#error $@ 4.7.0 $: 421 bad command

            the  session  is  terminated.  Note: it is a bad
            idea to return the original command in the error
            text  to  the client as that might be abused for
            certain attacks.  The ruleset cannot override  a
            rejection triggered by the built-in rules.

         5.1.4.6.  check_compat

                 The check_compat ruleset is passed

                sender-address $| recipient-address

            where  $|  is a metacharacter separating the ad-
            dresses.  It can accept or reject mail  transfer
            between these two addresses much like the check-
            compat() function.  Note:  while  other  check_*
            rulesets  are  invoked  during the SMTP mail re-
            ceiption  stage  (i.e.,  in  the  SMTP  server),
            check_compat is invoked during the mail delivery
            stage.

         5.1.4.7.  check_eoh

                 The check_eoh ruleset is passed

                number-of-headers $| size-of-headers

            where  $|  is  a  metacharacter  separating  the










Sendmail Installation and Operation Guide          SMM:08-67


            numbers.   These  numbers  can  be used for size
            comparisons with the arith map.  The ruleset  is
            triggered  after  all  of  the headers have been
            read.  It can be used to  correlate  information
            gathered  from  those  headers  using  the macro
            storage map.  One possible use is to check for a
            missing header.  For example:

                Kstorage macro
                HMessage-Id: $>CheckMessageId

                SCheckMessageId
                # Record the presence of the header
                R$*            $: $(storage {MessageIdCheck} $@ OK $) $1
                R< $+ @ $+ >   $@ OK
                R$*            $#error $: 553 Header Error

                Scheck_eoh
                # Check the macro
                R$*            $: < $&{MessageIdCheck} >
                # Clear the macro for the next message
                R$*            $: $(storage {MessageIdCheck} $) $1
                # Has a Message-Id: header
                R< $+ >        $@ OK
                # Allow missing Message-Id: from local mail
                R$*            $: < $&{client_name} >
                R< >           $@ OK
                R< $=w >       $@ OK
                # Otherwise, reject the mail
                R$*            $#error $: 553 Header Error

            Keep in mind the Message-Id: header is not a re-
            quired header and is not a guaranteed spam indi-
            cator.   This  ruleset  is an example and should
            probably not be used in production.

         5.1.4.8.  check_eom

                 The check_eom ruleset is called  after  the
            end  of  a message, its parameter is the message
            size.  It can accept or reject the message.

         5.1.4.9.  check_etrn

                 The check_etrn ruleset is passed the param-
            eter of the SMTP ETRN command.  It can accept or
            reject the command.

         5.1.4.10.  check_expn

                 The check_expn ruleset is passed  the  user
            name parameter of the SMTP EXPN command.  It can
            accept or reject the address.










SMM:08-68          Sendmail Installation and Operation Guide


         5.1.4.11.  check_vrfy

                 The check_vrfy ruleset is passed  the  user
            name parameter of the SMTP VRFY command.  It can
            accept or reject the command.

         5.1.4.12.  clt_features

                 The clt_features ruleset is called with the
            server's host name when sendmail connects to it.
            This ruleset should return $# followed by a list
            of options (single characters delimited by white
            space).  If the return value  starts  with  any-
            thing  else  it  is silently ignored.  Generally
            upper case characters turn off a  feature  while
            lower  case  characters  turn  it  on.   Options
            `D'/`M' cause the client to  not  use  DANE/MTA-
            STS,  respectively,  which is useful to interact
            with MTAs/MUs that have broken DANE/MTA-STS set-
            ups  by simply not using it.  Note: The d option
            in tls_clt_features to turn off  DANE  does  not
            work  when the server does not even offer START-
            TLS.

         5.1.4.13.  trust_auth

                 The trust_auth ruleset is passed the  AUTH=
            parameter  of the SMTP MAIL command.  It is used
            to  determine  whether  this  value  should   be
            trusted.  In  order  to  make this decision, the
            ruleset may make use of  the  various  ${auth_*}
            macros.  If the ruleset does resolve to the "er-
            ror" mailer the AUTH= parameter is  not  trusted
            and hence not passed on to the next relay.

         5.1.4.14.  tls_client

                 The tls_client ruleset is called when send-
            mail acts as server, after  a  STARTTLS  command
            has  been  issued, and from check_mail.  The pa-
            rameter is the value of ${verify}  and  STARTTLS
            or  MAIL, respectively.  If the ruleset does re-
            solve to the "error" mailer, the appropriate er-
            ror code is returned to the client.

         5.1.4.15.  tls_server

                 The tls_server ruleset is called when send-
            mail acts as client  after  a  STARTTLS  command
            (should) have been issued.  The parameter is the
            value of ${verify}.  If the ruleset does resolve
            to the "error" mailer, the connection is aborted
            (treated as non-deliverable with a permanent  or










Sendmail Installation and Operation Guide          SMM:08-69


            temporary error).

         5.1.4.16.  tls_rcpt

                 The  tls_rcpt  ruleset  is called each time
            before a RCPT command is sent.  The parameter is
            the  current recipient.  If the ruleset does re-
            solve to the "error" mailer, the RCPT command is
            suppressed  (treated  as  non-deliverable with a
            permanent or temporary error).  This ruleset al-
            lows  to  require  encryption or verification of
            the recipient's MTA even if the mail is  somehow
            redirected  to another host.  For example, send-
            ing mail to luke@endmail.org may get  redirected
            to   a  host  named  death.star  and  hence  the
            tls_server ruleset won't apply.  By  introducing
            per  recipient  restrictions such attacks (e.g.,
            via DNS spoofing) can be made  impossible.   See
            cf/README how this ruleset can be used.

         5.1.4.17.  srv_features

                 The srv_features ruleset is called with the
            connecting client's host name when a client con-
            nects  to  sendmail.  This ruleset should return
            $# followed by a list of options (single charac-
            ters  delimited  by white space).  If the return
            value starts with anything else it  is  silently
            ignored.   Generally  upper case characters turn
            off a feature while lower case  characters  turn
            it  on.  Option `S' causes the server not to of-
            fer STARTTLS, which is useful to  interact  with
            MTAs/MUAs  that have broken STARTTLS implementa-
            tions by simply not offering it.  `V' turns  off
            the  request for a client certificate during the
            TLS handshake.  Options  `A'  and  `P'  suppress
            SMTP  AUTH and PIPELINING, respectively.  `c' is
            the  equivalent  to  AuthOptions=p,   i.e.,   it
            doesn't  permit mechanisms susceptible to simple
            passive attack (e.g., PLAIN,  LOGIN),  unless  a
            security  layer  is active.  Option `l' requires
            SMTP AUTH for a connection.  Options  'B',  'D',
            'E',  and 'X' suppress SMTP VERB, DSN, ETRN, and
            EXPN, respectively.  If a client  sends  one  of
            the  (HTTP) commands GET, POST, CONNECT, or USER
            the connection is immediately terminated in  the
            following  cases:  if  sent as first command, if
            sent as first command after STARTTLS, or if  the
            'h' option is set.














SMM:08-70          Sendmail Installation and Operation Guide


                A        Do not offer AUTH
                a        Offer AUTH (default)
                B        Do not offer VERB
                b        Offer VERB (default)
                C        Do not require security layer for
                         plaintext AUTH (default)
                c        Require security layer for plaintext AUTH
                D        Do not offer DSN
                d        Offer DSN (default)
                E        Do not offer ETRN
                e        Offer ETRN (default)
                h        Terminate session after HTTP commands
                L        Do not require AUTH (default)
                l        Require AUTH
                P        Do not offer PIPELINING
                p        Offer PIPELINING (default)
                S        Do not offer STARTTLS
                s        Offer STARTTLS (default)
                V        Do not request a client certificate
                v        Request a client certificate (default)
                X        Do not offer EXPN
                x        Offer EXPN (default)

            Note:  the  entries  marked as ``(default)'' may
            require that some configuration has  been  made,
            e.g.,  SMTP  AUTH  is only available if properly
            configured.   Moreover,  many  options  can   be
            changed  on a global basis via other settings as
            explained in this document, e.g., via DaemonPor-
            tOptions.

                 The ruleset may return `$#temp' to indicate
            that there is a  temporary  problem  determining
            the correct features, e.g., if a map is unavail-
            able.  In that case, the SMTP  server  issues  a
            temporary failure and does not accept email.

         5.1.4.18.  try_tls

                 The try_tls ruleset is called when sendmail
            connects to another MTA.  If  the  ruleset  does
            resolve to the "error" mailer, sendmail does not
            try STARTTLS even if it  is  offered.   This  is
            useful  to  deal  with STARTTLS interoperability
            issues by simply not using it.

         5.1.4.19.  tls_srv_features and tls_clt_features

                 The  tls_clt_features  ruleset  is   called
            right  before  sendmail issues the STARTTLS com-
            mand to another  MTA  and  the  tls_srv_features
            ruleset is called when a client sends the START-
            TLS command to sendmail.  The arguments for  the










Sendmail Installation and Operation Guide          SMM:08-71


            rulesets are the host name and IP address of the
            other side separated by $| (which is a metachar-
            acter).   They should return a list of key=value
            pairs separated by semicolons; the list  can  be
            empty  if  no  options  should be applied to the
            connection.  Available keys are  and  their  al-
            lowed values are:

            Options
              A comma separated list of SSL related options.
              See ServerSSLOptions and ClientSSLOptions  for
              details,  as  well  as  SSL_set_options(3) and
              note this warning: Options already set  before
              are not cleared!

            CipherList
              Specify cipher list for STARTTLS (does not ap-
              ply to TLSv1.3), see ciphers(1)  for  possible
              values.   This overrides the global CipherList
              for the session.

            CertFile
              File containing a certificate.

            KeyFile
              File containing the private key for  the  cer-
              tificate.

            Flags
              Currently the only valid flags are
              R  to  require a CRL for each encountered cer-
              tificate during  verification  (by  default  a
              missing CRL is ignored),
              c and C which basically clears/sets the option
              TLSFallbacktoClear for just this session,  re-
              spectively,
              d  to  turn  off  DANE which is obviously only
              valid for tls_clt_features and  requires  DANE
              to  be  compiled  in.  This might be needed in
              case of a misconfiguration,  e.g.,  specifying
              invalid TLSA RRs.

            Example:

                Stls_srv_features
                R$* $| 10.$+   $: cipherlist=HIGH


            Notes:

                 Errors  in  these  features  (e.g., unknown
            keys or invalid values) are logged and the  cur-
            rent  session is aborted to avoid using STARTTLS










SMM:08-72          Sendmail Installation and Operation Guide


            with features that should have been changed.

                 The keys are case-insensitive.

                 Both CertFile and KeyFile must be specified
            together; specifying only one is an error.

         5.1.4.20.  authinfo

                 The  authinfo  ruleset is called when send-
            mail tries to authenticate to another  MTA.   It
            should  return  $#  followed by a list of tokens
            that are used for  SMTP  AUTH.   If  the  return
            value  starts  with anything else it is silently
            ignored.  Each token is a tagged string  of  the
            form: "TDstring" (including the quotes), where

                T        Tag which describes the item
                D        Delimiter: ':' simple text follows
                         '=' string is base64 encoded
                string   Value of the item

            Valid values for the tag are:

                U        user (authorization) id
                I        authentication id
                P        password
                R        realm
                M        list of mechanisms delimited by spaces

            If  this ruleset is defined, the option Default-
            AuthInfo is ignored (even if  the  ruleset  does
            not return a ``useful'' result).

         5.1.4.21.  queuegroup

                 The queuegroup ruleset is used to map a re-
            cipient address to a queue group name.  The  in-
            put  for  the  ruleset  is the recipient address
            (i.e., the address part of the resolved  triple)
            The  ruleset  should  return  $# followed by the
            name of a queue  group.   If  the  return  value
            starts  with  anything  else  it is silently ig-
            nored.  See the section about ``Queue Groups and
            Queue Directories'' for further information.

         5.1.4.22.  greet_pause

                 The  greet_pause ruleset is used to specify
            the amount of time to pause before  sending  the
            initial  SMTP  220  greeting.  If any traffic is
            received during that pause, an SMTP  554  rejec-
            tion  response  is  given  instead  of  the  220










Sendmail Installation and Operation Guide          SMM:08-73


            greeting and all SMTP commands are rejected dur-
            ing  that  connection.  This helps protect sites
            from open proxies and SMTP slammers.  The  rule-
            set  should  return $# followed by the number of
            milliseconds (thousandths of a second) to pause.
            If the return value starts with anything else or
            is not a number, it is silently ignored.   Note:
            this  ruleset is not invoked (and hence the fea-
            ture is disabled) when smtps (SMTP over SSL)  is
            used, i.e., the s modifier is set for the daemon
            via DaemonPortOptions, because in this case  the
            SSL  handshake  is performed before the greeting
            is sent.

      5.1.5.  IPC mailers

              Some special processing occurs if the  ruleset
         zero  resolves  to an IPC mailer (that is, a mailer
         that has "[IPC]" listed as the Path in the  M  con-
         figuration  line.   The host name passed after "$@"
         has MX expansion performed if not delivering via  a
         named socket; this looks the name up in DNS to find
         alternate delivery sites.

              The host name can also be provided as a dotted
         quad or an IPv6 address in square brackets; for ex-
         ample:

             [128.32.149.78]

         or

             [IPv6:2002:c0a8:51d2::23f4]

         This causes direct conversion of the numeric  value
         to an IP host address.

              The  host  name  passed  in after the "$@" may
         also be a colon or comma separated list  of  hosts.
         Each  is separately MX expanded and the results are
         concatenated to  make  (essentially)  one  long  MX
         list.   Hosts separated by a comma have the same MX
         preference, and for each colon separated  host  the
         MX  preference is increased.  The intent here is to
         create "fake" MX records that are not published  in
         DNS for private internal networks.

              As  a final special case, the host name can be
         passed in as a text string in square brackets:

             [ucbvax.berkeley.edu]

         This form avoids the MX  mapping.   N.B.:  This  is










SMM:08-74          Sendmail Installation and Operation Guide


         intended  only for situations where you have a net-
         work firewall or other host that  will  do  special
         processing  for  all  your  mail,  so  that your MX
         record points to a gateway  machine;  this  machine
         could  then  do  direct delivery to machines within
         your local domain.  Use of  this  feature  directly
         violates  RFC  1123 section 5.3.5: it should not be
         used lightly.

   5.2.  D -- Define Macro

           Macros are named with a single character or  with
      a  word  in {braces}.  The names ``x'' and ``{x}'' de-
      note the same macro for every single character  ``x''.
      Single character names may be selected from the entire
      ASCII set, but user-defined macros should be  selected
      from  the  set of upper case letters only.  Lower case
      letters and special symbols are used internally.  Long
      names beginning with a lower case letter or a punctua-
      tion character are reserved for use  by  sendmail,  so
      user-defined long macro names should begin with an up-
      per case letter.

           The syntax for macro definitions is:

          Dxval

      where x is the name of the macro (which may be a  sin-
      gle  character  or  a  word  in braces) and val is the
      value it should have.  There should be no spaces given
      that do not actually belong in the macro value.

           Macros  are  interpolated using the construct $x,
      where x is the name of the macro to  be  interpolated.
      This interpolation is done when the configuration file
      is read, except in M lines.  The special construct $&x
      can be used in R lines to get deferred interpolation.

           Conditionals can be specified using the syntax:

          $?x text1 $| text2 $.

      This  interpolates  text1  if  the macro $x is set and
      non-null, and text2 otherwise.  The "else" ($|) clause
      may be omitted.

           The  following macros are defined and/or used in-
      ternally by sendmail for interpolation into argv's for
      mailers  or for other contexts.  The ones marked * are














Sendmail Installation and Operation Guide          SMM:08-75


      information passed into sendmail[16], the ones  marked
      #  are information passed both in and out of sendmail,
      and the unmarked macros are passed out of sendmail but
      are not otherwise used internally.  These macros are:

      $a   The  origination date in RFC 822 format.  This is
           extracted from the Date: line.

      $b   The current date in RFC 822 format.

      $c   The hop count.  This is a count of the number  of
           Received:  lines plus the value of the -h command
           line flag.

      $d   The current date in UNIX (ctime) format.

      $e*  (Obsolete;  use  SmtpGreetingMessage  option  in-
           stead.)  The SMTP entry message.  This is printed
           out when SMTP starts up.  The first word must  be
           the  $j  macro as specified by RFC 821.  Defaults
           to "$j Sendmail $v ready at $b".  Commonly  rede-
           fined  to  include the configuration version num-
           ber, e.g., "$j Sendmail $v/$Z ready at $b"

      $f   The envelope sender (from) address.

      $g   The sender address  relative  to  the  recipient.
           For   example,   if  $f  is  "foo",  $g  will  be
           "host!foo", "foo@host.domain", or whatever is ap-
           propriate for the receiving mailer.

      $h   The  recipient  host.   This  is set in ruleset 0
           from the $@ field of a parsed address.

      $i   The queue id, e.g., "f344MXxp018717".

      $j#  The "official" domain name for this  site.   This
           is  fully qualified if the full qualification can
           be found.  It must be redefined to be  the  fully
           qualified  domain name if your system is not con-
           figured so that information can find it automati-
           cally.

      $k   The UUCP node name (from the uname system call).

      $l*  (Obsolete; use UnixFromLine option instead.)  The
           format of the UNIX from line.   Unless  you  have
           changed  the  UNIX mailbox format, you should not
____________________
   [16]As of version 8.6, all of these macros  have  reason-
able  defaults.  Previous versions required that they be de-
fined.











SMM:08-76          Sendmail Installation and Operation Guide


           change the default, which is "From $g $d".

      $m   The domain part of the gethostname return  value.
           Under  normal  circumstances, $j is equivalent to
           $w.$m.

      $n*  The name of the daemon (for error messages).  De-
           faults to "MAILER-DAEMON".

      $o*  (Obsolete:  use  OperatorChars  option  instead.)
           The set of "operators" in addresses.  A  list  of
           characters  which  will  be considered tokens and
           which will separate tokens  when  doing  parsing.
           For  example,  if  "@" were in the $o macro, then
           the input "a@b" would be scanned as three tokens:
           "a," "@," and "b."  Defaults to ".:@[]", which is
           the minimum set necessary to do RFC 822  parsing;
           a  richer  set  of operators is ".:%@!/[]", which
           adds support for UUCP, the %-hack, and X.400  ad-
           dresses.

      $p   Sendmail's process id.

      $q*  Default  format  of sender address.  The $q macro
           specifies how an address should appear in a  mes-
           sage  when  it is defaulted.  Defaults to "<$g>".
           It is commonly redefined to be "$?x$x <$g>$|$g$."
           or "$g$?x ($x)$.", corresponding to the following
           two formats:

               Eric Allman <eric@CS.Berkeley.EDU>
               eric@CS.Berkeley.EDU (Eric Allman)

           Sendmail properly quotes names that have  special
           characters if the first form is used.

      $r   Protocol  used  to receive the message.  Set from
           the -p command line flag or by  the  SMTP  server
           code.

      $s   Sender's host name.  Set from the -p command line
           flag or by the SMTP server code (in which case it
           is set to the EHLO/HELO parameter).

      $t   A  numeric  representation of the current time in
           the format YYYYMMDDHHmm (4 digit year  1900-9999,
           2  digit  month 01-12, 2 digit day 01-31, 2 digit
           hours 00-23, 2 digit minutes 00-59).

      $u   The recipient user.

      $v   The version number of the sendmail binary.











Sendmail Installation and Operation Guide          SMM:08-77


      $w#  The hostname of this site.  This is the root name
           of this host (but see below for caveats).

      $x   The full name of the sender.

      $z   The home directory of the recipient.

      $_   The   validated   sender   address.    See   also
           ${client_resolve}.

      ${addr_type}
           The type of the address which is currently  being
           rewritten.  This macro contains up to three char-
           acters, the first is either `e' or `h' for  enve-
           lope/header  address,  the second is a space, and
           the third is either `s' or `r' for sender/recipi-
           ent address.

      ${alg_bits}
           The  maximum keylength (in bits) of the symmetric
           encryption algorithm used for a  TLS  connection.
           This  may  be  less than the effective keylength,
           which is stored in ${cipher_bits},  for  ``export
           controlled'' algorithms.

      ${auth_authen}
           The client's authentication credentials as deter-
           mined by authentication (only set if successful).
           The  format  depends  on  the  mechanism used, it
           might be just `user', or `user@realm',  or  some-
           thing similar (SMTP AUTH only).

      ${auth_author}
           The authorization identity, i.e. the AUTH= param-
           eter of the SMTP MAIL command if supplied.

      ${auth_type}
           The mechanism used for SMTP authentication  (only
           set if successful).

      ${auth_ssf}
           The  keylength (in bits) of the symmetric encryp-
           tion algorithm used for the security layer  of  a
           SASL mechanism.

      ${bodytype}
           The  message body type (7BIT or 8BITMIME), as de-
           termined from the envelope.

      ${cert_fp}
           The  fingerprint  of  the  presented  certificate
           (STARTTLS  only).   Note:  this macro is only de-
           fined if the option  CertFingerprintAlgorithm  is










SMM:08-78          Sendmail Installation and Operation Guide


           set,  in which case the specified fingerprint al-
           gorithm is used.  The valid algorithms depend  on
           the  OpenSSL  version, but usually md5, sha1, and
           sha256 are available.  See

               openssl dgst -h

           for a list.

      ${cert_issuer}
           The DN (distinguished name) of the  CA  (certifi-
           cate  authority)  that  signed the presented cer-
           tificate (the cert issuer) (STARTTLS only).

      ${cert_md5}
           The MD5 hash of the presented certificate (START-
           TLS  only).   Note: this macro is only defined if
           the option CertFingerprintAlgorithm is not set.

      ${cert_subject}
           The DN of the presented certificate  (called  the
           cert subject) (STARTTLS only).

      ${cipher}
           The  cipher  suite used for the connection, e.g.,
           EDH-DSS-DES-CBC3-SHA,  EDH-RSA-DES-CBC-SHA,  DES-
           CBC-MD5, DES-CBC3-SHA (STARTTLS only).

      ${cipher_bits}
           The  effective keylength (in bits) of the symmet-
           ric encryption algorithm used for a  TLS  connec-
           tion.

      ${client_addr}
           The  IP  address  of  the  SMTP client.  IPv6 ad-
           dresses are tagged with "IPv6:"  before  the  ad-
           dress.  Defined in the SMTP server only.

      ${client_connections}
           The number of open connections in the SMTP server
           for the client IP address.

      ${client_flags}
           The flags specified  by  the  Modifier=  part  of
           ClientPortOptions  where flags are separated from
           each other by spaces and  upper  case  flags  are
           doubled.   That  is,  Modifier=hA  will be repre-
           sented as "h AA" in ${client_flags}, which is re-
           quired for testing the flags in rulesets.

      ${client_name}
           The  host  name  of the SMTP client.  This may be
           the client's bracketed IP address in the  form  [










Sendmail Installation and Operation Guide          SMM:08-79


           nnn.nnn.nnn.nnn     ]     for    IPv4    and    [
           IPv6:nnnn:...:nnnn ] for IPv6 if the client's  IP
           address is not resolvable, or if it is resolvable
           but the  IP  address  of  the  resolved  hostname
           doesn't  match  the original IP address.  Defined
           in the SMTP server only.  See  also  ${client_re-
           solve}.

      ${client_port}
           The  port  number of the SMTP client.  Defined in
           the SMTP server only.

      ${client_ptr}
           The result of the PTR lookup for  the  client  IP
           address.     Note:    this   is   the   same   as
           ${client_name} if and only  if  ${client_resolve}
           is OK.  Defined in the SMTP server only.

      ${client_rate}
           The number of incoming connections for the client
           IP address over the time  interval  specified  by
           ConnectionRateWindowSize.

      ${client_resolve}
           Holds   the   result  of  the  resolve  call  for
           ${client_name}.  Possible values are:

               OK        resolved successfully
               FAIL      permanent lookup failure
               FORGED    forward lookup doesn't match reverse lookup
               TEMP      temporary lookup failure

           Defined in the SMTP server only.   sendmail  per-
           forms  a hostname lookup on the IP address of the
           connecting client.  Next the IP addresses of that
           hostname are looked up.  If the client IP address
           does not appear in that list, then  the  hostname
           is  maybe forged.  This is reflected as the value
           FORGED for ${client_resolve} and it also shows up
           in $_ as "(may be forged)".

      ${cn_issuer}
           The  CN  (common  name) of the CA that signed the
           presented certificate (STARTTLS only).  Note:  if
           the  CN  cannot  be extracted properly it will be
           replaced by one of these strings based on the en-
           countered error:

               BadCertificateContainsNULCN contains a NUL character
               BadCertificateTooLong    CN is too long
               BadCertificateUnknown    CN could not be extracted

           In  the  last case, some other (unspecific) error










SMM:08-80          Sendmail Installation and Operation Guide


           occurred.

      ${cn_subject}
           The CN (common name) of the presented certificate
           (STARTTLS  only).   See ${cn_issuer} for possible
           replacements.

      ${currHeader}
           Header value as quoted string (possibly truncated
           to  MAXNAME).   This  macro  is only available in
           header check rulesets.

      ${daemon_addr}
           The IP address the daemon  is  listening  on  for
           connections.

      ${daemon_family}
           The  network  family  if  the daemon is accepting
           network  connections.   Possible  values  include
           "inet", "inet6", "iso", "ns", "x.25"

      ${daemon_flags}
           The flags for the daemon as specified by the Mod-
           ifier=  part  of  DaemonPortOptions  whereby  the
           flags  are  separated  from each other by spaces,
           and upper case flags are doubled.  That is, Modi-
           fier=Ea  will  be represented as "EE a" in ${dae-
           mon_flags}, which is  required  for  testing  the
           flags in rulesets.

      ${daemon_info}
           Some information about a daemon as a text string.
           For example, "SMTP+queueing@00:30:00".

      ${daemon_name}
           The name of  the  daemon  from  DaemonPortOptions
           Name=  suboption.   If this suboption is not set,
           "Daemon#", where # is the daemon number, is used.

      ${daemon_port}
           The port the daemon is accepting  connection  on.
           Unless  DaemonPortOptions  is set, this will most
           likely be "25".

      ${deliveryMode}
           The current delivery mode sendmail is using.   It
           is initially set to the value of the DeliveryMode
           option.

      ${dsn_envid}
           The envelope  id  parameter  (ENVID=)  passed  to
           sendmail as part of the envelope.











Sendmail Installation and Operation Guide          SMM:08-81


      ${dsn_notify}
           Value  of  DSN NOTIFY= parameter (never, success,
           failure, delay, or empty string).

      ${dsn_ret}
           Value of DSN RET= parameter (hdrs, full, or empty
           string).

      ${envid}
           The  envelope  id  parameter  (ENVID=)  passed to
           sendmail as part of the envelope.

      ${hdrlen}
           The length of the header value which is stored in
           ${currHeader}  (before  possible truncation).  If
           this value is greater than or  equal  to  MAXNAME
           the header has been truncated.

      ${hdr_name}
           The  name  of the header field for which the cur-
           rent header check ruleset has been called.   This
           is  useful  for a default header check ruleset to
           get the name of the header;  the  macro  is  only
           available in header check rulesets.

      ${if_addr}
           The  IP  address  of the interface of an incoming
           connection unless it  is  in  the  loopback  net.
           IPv6 addresses are tagged with "IPv6:" before the
           address.

      ${if_addr_out}
           The IP address of the interface  of  an  outgoing
           connection  unless  it  is  in  the loopback net.
           IPv6 addresses are tagged with "IPv6:" before the
           address.

      ${if_family}
           The  IP  family  of  the interface of an incoming
           connection unless it is in the loopback net.

      ${if_family_out}
           The IP family of the  interface  of  an  outgoing
           connection unless it is in the loopback net.

      ${if_name}
           The  hostname associated with the interface of an
           incoming connection.  This macro can be used  for
           SmtpGreetingMessage  and  HReceived  for  virtual
           hosting.  For example:

               O SmtpGreetingMessage=$?{if_name}${if_name}$|$j$. MTA











SMM:08-82          Sendmail Installation and Operation Guide


      ${if_name_out}
           The name of the interface of an outgoing  connec-
           tion.

      ${load_avg}
           The current load average.

      ${mail_addr}
           The  address  part  of the resolved triple of the
           address given for the SMTP MAIL command.  Defined
           in the SMTP server only.

      ${mail_host}
           The  host from the resolved triple of the address
           given for the SMTP MAIL command.  Defined in  the
           SMTP server only.

      ${mail_mailer}
           The  mailer  from  the resolved triple of the ad-
           dress given for the SMTP MAIL  command.   Defined
           in the SMTP server only.

      ${msg_id}
           The value of the Message-Id: header.

      ${msg_size}
           The  value  of the SIZE= parameter, i.e., usually
           the size of the message (in an  ESMTP  dialogue),
           before the message has been collected, thereafter
           the message size as computed by sendmail (and can
           be used in check_compat).

      ${nbadrcpts}
           The  number  of  bad recipients for a single mes-
           sage.

      ${nrcpts}
           The number of validated recipients for  a  single
           message.   Note:  since recipient validation hap-
           pens after check_rcpt has been called, the  value
           in  this  ruleset  is one less than what might be
           expected.

      ${ntries}
           The number of delivery attempts.

      ${opMode}
           The current operation mode (from the -b flag).

      ${quarantine}
           The quarantine reason for the envelope, if it  is
           quarantined.











Sendmail Installation and Operation Guide          SMM:08-83


      ${queue_interval}
           The queue run interval given by the -q flag.  For
           example, -q30m  would  set  ${queue_interval}  to
           "00:30:00".

      ${rcpt_addr}
           The  address  part  of the resolved triple of the
           address given for the SMTP RCPT command.  Defined
           in the SMTP server only after a RCPT command.

      ${rcpt_host}
           The  host from the resolved triple of the address
           given for the SMTP RCPT command.  Defined in  the
           SMTP server only after a RCPT command.

      ${rcpt_mailer}
           The  mailer  from  the resolved triple of the ad-
           dress given for the SMTP RCPT  command.   Defined
           in the SMTP server only after a RCPT command.

      ${server_addr}
           The address of the server of the current outgoing
           SMTP connection.  For LMTP delivery the macro  is
           set to the name of the mailer.  (only if sendmail
           is compiled with STARTTLS or SASL.)

      ${server_name}
           The name of the server of  the  current  outgoing
           SMTP  or  LMTP  connection.  (only if sendmail is
           compiled with STARTTLS or SASL.)

      ${time}
           The output of the  time(3)  function,  i.e.,  the
           number  of  seconds  since  0 hours, 0 minutes, 0
           seconds, January 1, 1970,  Coordinated  Universal
           Time (UTC).

      ${tls_version}
           The  TLS/SSL  version  used  for  the connection,
           e.g., TLSv1.2, TLSv1; defined after STARTTLS  has
           been used.

      ${total_rate}
           The total number of incoming connections over the
           time interval specified by  ConnectionRateWindow-
           Size.

      ${verify}
           The  result  of the verification of the presented
           cert; only defined after STARTTLS has  been  used
           (or attempted).  Possible values are:












SMM:08-84          Sendmail Installation and Operation Guide


               TRUSTED      verification via DANE succeeded.
               OK           verification succeeded.
               NO           no cert presented.
               NOT          no cert requested.
               FAIL         cert presented but could not be verified,
                            e.g., the signing CA is missing.
               NONE         STARTTLS has not been performed.
               CLEAR        STARTTLS has been disabled internally for a clear text delivery attempt.
               TEMP         temporary error occurred.
               PROTOCOL     some protocol error occurred
                            at the ESMTP level (not TLS).
               SOFTWARE     STARTTLS handshake failed,
                            which is a fatal error for this session,
                            the e-mail will be queued.


           There  are three types of dates that can be used.
      The $a and $b macros are in RFC 822 format; $a is  the
      time as extracted from the "Date:" line of the message
      (if there was one), and $b is  the  current  date  and
      time  (used  for  postmarks).   If  no "Date:" line is
      found in the incoming message, $a is set to  the  cur-
      rent  time also.  The $d macro is equivalent to the $b
      macro in UNIX (ctime) format.

           The macros $w, $j, and $m are set to the identity
      of this host.  Sendmail tries to find the fully quali-
      fied name of the host if at all possible; it does this
      by  calling gethostname(2) to get the current hostname
      and then passing that  to  gethostbyname(3)  which  is
      supposed  to return the canonical version of that host
      name.[17] Assuming this is successful, $j  is  set  to
      the  fully  qualified name and $m is set to the domain
      part of the name (everything  after  the  first  dot).
      The  $w macro is set to the first word (everything be-
      fore the first dot) if you have a level  5  or  higher
      configuration  file;  otherwise, it is set to the same
      value as $j.  If the canonification is not successful,
      it  is  imperative  that the config file set $j to the
      fully qualified domain name[18].

           The  $f  macro  is the id of the sender as origi-
      nally determined; when mailing to a specific host  the
      $g  macro is set to the address of the sender relative
      to  the  recipient.   For  example,  if  I   send   to
____________________
   [17]For example, on some systems gethostname might return
"foo"  which  would be mapped to "foo.bar.com" by gethostby-
name.
   [18]Older versions of sendmail didn't  pre-define  $j  at
all, so up until 8.6, config files always had to define $j.












Sendmail Installation and Operation Guide          SMM:08-85


      "bollard@matisse.CS.Berkeley.EDU"   from  the  machine
      "vangogh.CS.Berkeley.EDU" the $f macro will be  "eric"
      and  the  $g  macro  will  be  "eric@vangogh.CS.Berke-
      ley.EDU."

           The $x macro is set  to  the  full  name  of  the
      sender.   This  can be determined in several ways.  It
      can be passed as flag to sendmail.  It can be  defined
      in the NAME environment variable.  The third choice is
      the value of the "Full-Name:" line in the header if it
      exists,  and the fourth choice is the comment field of
      a "From:" line.  If all of these fail, and if the mes-
      sage  is  being  originated  locally, the full name is
      looked up in the /etc/passwd file.

           When sending, the $h, $u, and $z macros  get  set
      to  the  host,  user, and home directory (if local) of
      the recipient.  The first two are set from the $@  and
      $: part of the rewriting rules, respectively.

           The  $p  and  $t macros are used to create unique
      strings (e.g., for the "Message-Id:" field).   The  $i
      macro is set to the queue id on this host; if put into
      the timestamp line it  can  be  extremely  useful  for
      tracking messages.  The $v macro is set to be the ver-
      sion number of sendmail; this is normally put in time-
      stamps and has been proven extremely useful for debug-
      ging.

           The $c field is set to the "hop count," i.e., the
      number of times this message has been processed.  This
      can be determined by the -h flag on the  command  line
      or by counting the timestamps in the message.

           The $r and $s fields are set to the protocol used
      to communicate with sendmail and the sending hostname.
      They  can  be  set  together using the -p command line
      flag or separately using the -M or -oM flags.

           The $_ is set to a validated  sender  host  name.
      If  the  sender is running an RFC 1413 compliant IDENT
      server and the receiver has the IDENT protocol  turned
      on, it will include the user name on that host.

           The     ${client_name},    ${client_addr},    and
      ${client_port} macros are set to  the  name,  address,
      and  port  number  of  the SMTP client who is invoking
      sendmail as a  server.   These  can  be  used  in  the
      check_*  rulesets  (using  the  $& deferred evaluation
      form, of course!).













SMM:08-86          Sendmail Installation and Operation Guide


   5.3.  C and F -- Define Classes

           Classes of phrases may be defined to match on the
      left hand side of rewriting rules, where a "phrase" is
      a sequence of characters that does not  contain  space
      characters.   For  example  a class of all local names
      for this site might be created  so  that  attempts  to
      send  to  oneself can be eliminated.  These can either
      be defined directly in the configuration file or  read
      in  from  another file.  Classes are named as a single
      letter or a word in {braces}.  Class  names  beginning
      with lower case letters and special characters are re-
      served for system  use.   Classes  defined  in  config
      files  may  be  given names from the set of upper case
      letters for short names or  beginning  with  an  upper
      case letter for long names.

           The syntax is:

          Ccphrase1 phrase2...
          Fcfile
          Fc|program
          Fc[mapkey]@mapclass:mapspec

      The first form defines the class c to match any of the
      named words.  If phrase1 or phrase2 is another  class,
      e.g.,  $=S, the contents of class S are added to class
      c.  It is permissible to  split  them  among  multiple
      lines; for example, the two forms:

          CHmonet ucbmonet

      and

          CHmonet
          CHucbmonet

      are  equivalent.  The ``F'' forms read the elements of
      the class c from the named file, program, or map spec-
      ification.   Each  element should be listed on a sepa-
      rate line.  To specify an optional  file,  use  ``-o''
      between the class name and the file name, e.g.,

          Fc -o /path/to/file

      If  the file can't be used, sendmail will not complain
      but silently ignore it.  The map form should be an op-
      tional  map  key, an at sign, and a map class followed
      by the specification for that map.  Examples include:

          F{VirtHosts}@ldap:-k (&(objectClass=virtHosts)(host=*)) -v host
          F{MyClass}foo@hash:/etc/mail/classes











Sendmail Installation and Operation Guide          SMM:08-87


      will fill the class $={VirtHosts}  from  an  LDAP  map
      lookup and $={MyClass} from a hash database map lookup
      of the foo.  There is also a built-in schema that  can
      be accessed by only specifying:

          F{ClassName}@LDAP

      This will tell sendmail to use the default schema:

          -k (&(objectClass=sendmailMTAClass)
               (sendmailMTAClassName=ClassName)
               (|(sendmailMTACluster=${sendmailMTACluster})
                 (sendmailMTAHost=$j)))
          -v sendmailMTAClassValue

      Note  that  the  lookup  is only done when sendmail is
      initially started.

           Elements of classes can be accessed in rules  us-
      ing  $=  or  $~.   The $~ (match entries not in class)
      only matches a single word; multi-word entries in  the
      class are ignored in this context.

           Some classes have internal meaning to sendmail:

      $=e  contains  the Content-Transfer-Encodings that can
           be 8->7 bit encoded.  It is predefined to contain
           "7bit", "8bit", and "binary".

      $=k  set  to be the same as $k, that is, the UUCP node
           name.

      $=m  set to the set of domains by which this  host  is
           known, initially just $m.

      $=n  can be set to the set of MIME body types that can
           never be eight to seven bit encoded.  It defaults
           to "multipart/signed".  Message types "message/*"
           and "multipart/*"  are  never  encoded  directly.
           Multipart  messages  are  always  handled  recur-
           sively.  The handling of message/*  messages  are
           controlled by class $=s.

      $=q  A set of Content-Types that will never be encoded
           as base64 (if they have to be encoded, they  will
           be  encoded  as  quoted-printable).   It can have
           primary types (e.g., "text") or full types  (such
           as "text/plain").

      $=s  contains  the set of subtypes of message that can
           be treated recursively.  By default  it  contains
           only "rfc822".  Other "message/*" types cannot be
           8->7 bit encoded.  If a message containing  eight










SMM:08-88          Sendmail Installation and Operation Guide


           bit  data  is  sent to a seven bit host, and that
           message cannot be encoded  into  seven  bits,  it
           will be stripped to 7 bits.

      $=t  set to the set of trusted users by the T configu-
           ration line.  If you want to read  trusted  users
           from a file, use Ft/file/name.

      $=w  set to be the set of all names this host is known
           by.  This can be used to match local hostnames.

      $={persistentMacros}
           set to the macros that  should  be  saved  across
           queue  runs.   Care  should  be taken when adding
           macro names to this class.

           Sendmail can be  compiled  to  allow  a  scanf(3)
      string  on  the  F  line.  This lets you do simplistic
      parsing of text files.  For example, to read  all  the
      user  names  in  your  system  /etc/passwd file into a
      class, use

          FL/etc/passwd %[^:]

      which reads every line up to the first colon.

   5.4.  M -- Define Mailer

           Programs and interfaces to mailers are defined in
      this line.  The format is:

          Mname, {field=value}*

      where  name is the name of the mailer (used internally
      only) and the "field=name" pairs define attributes  of
      the mailer.  Fields are:



























Sendmail Installation and Operation Guide          SMM:08-89


          Path      The pathname of the mailer
          Flags     Special flags for this mailer
          Sender    Rewriting set(s) for sender addresses
          Recipient Rewriting set(s) for recipient addresses
          recipientsMaximum number of recipients per connection
          Argv      An argument vector to pass to this mailer
          Eol       The end-of-line string for this mailer
          Maxsize   The maximum message length to this mailer
          maxmessagesThe maximum message deliveries per connection
          Linelimit The maximum line length in the message body
          Directory The working directory for the mailer
          Userid    The default user and group id to run as
          Nice      The nice(2) increment for the mailer
          Charset   The default character set for 8-bit characters
          Type      Type information for DSN diagnostics
          Wait      The maximum time to wait for the mailer
          QueuegroupThe default queue group for the mailer
          /         The root directory for the mailer

      Only  the first character of the field name is checked
      (it's case-sensitive).

           The following flags may be set in the mailer  de-
      scription.  Any other flags may be used freely to con-
      ditionally assign headers  to  messages  destined  for
      particular  mailers.   Flags marked with * are not in-
      terpreted by the sendmail binary; these are  the  con-
      ventionally  used to correlate to the flags portion of
      the H line.  Flags marked with # apply to the  mailers
      for the sender address rather than the usual recipient
      mailers.

      a   Run Extended SMTP  (ESMTP)  protocol  (defined  in
          RFCs 1869, 1652, and 1870).  This flag defaults on
          if the SMTP greeting  message  includes  the  word
          "ESMTP".

      A   Look  up  the  user (address) part of the resolved
          mailer triple, in the  alias  database.   Normally
          this is only set for local mailers.

      b   Force  a blank line on the end of a message.  This
          is intended to work around some stupid versions of
          /bin/mail  that  require  a blank line, but do not
          provide it themselves.  It would not  normally  be
          used on network mail.

      B   Strip  leading backslashes (\) off of the address;
          this is a subset of the  functionality  of  the  s
          flag.

      c   Do not include comments in addresses.  This should
          only be used if you have to work around  a  remote










SMM:08-90          Sendmail Installation and Operation Guide


          mailer  that  gets  confused  by  comments.   This
          strips addresses of the form "Phrase <address>" or
          "address (Comment)" down to just "address".

      C#  If  mail  is received from a mailer with this flag
          set, any addresses in the header that do not  have
          an  at sign ("@") after being rewritten by ruleset
          three will have  the  "@domain"  clause  from  the
          sender  envelope  address  tacked on.  This allows
          mail with headers of the form:

              From: usera@hosta
              To: userb@hostb, userc

          to be rewritten as:

              From: usera@hosta
              To: userb@hostb, userc@hosta

          automatically.  However, it  doesn't  really  work
          reliably.

      d   Do not include angle brackets around route-address
          syntax addresses.  This is useful on mailers  that
          are  going to pass addresses to a shell that might
          interpret angle brackets as I/O redirection.  How-
          ever,  it  does  not  protect  against other shell
          metacharacters.  Therefore, passing addresses to a
          shell should not be considered secure.

      D*  This mailer wants a "Date:" header line.

      e   This  mailer is expensive to connect to, so try to
          avoid connecting normally; any  necessary  connec-
          tion  will occur during a queue run.  See also op-
          tion HoldExpensive.

      E   Escape lines beginning with "From " in the message
          with a `>' sign.

      f   The  mailer wants a -f from flag, but only if this
          is a network forward operation (i.e.,  the  mailer
          will  give an error if the executing user does not
          have special permissions).

      F*  This mailer wants a "From:" header line.

      g   Normally,  sendmail  sends  internally   generated
          email (e.g., error messages) using the null return
          address as required by RFC  1123.   However,  some
          mailers  don't  accept  a null return address.  If
          necessary, you can set the g flag to prevent send-
          mail  from  obeying  the standards; error messages










Sendmail Installation and Operation Guide          SMM:08-91


          will be sent as from the MAILER-DAEMON  (actually,
          the value of the $n macro).

      h   Upper  case should be preserved in host names (the
          $@ portion of the  mailer  triplet  resolved  from
          ruleset 0) for this mailer.

      i   Do  User Database rewriting on envelope sender ad-
          dress.

      I   This flag is deprecated and will be removed from a
          future version.  This mailer will be speaking SMTP
          to another sendmail -- as such it can use  special
          protocol  features.   This flag should not be used
          except for debugging purposes because it uses VERB
          as SMTP command.

      j   Do  User  Database rewriting on recipients as well
          as senders.

      k   Normally when sendmail  connects  to  a  host  via
          SMTP, it checks to make sure that this isn't acci-
          dentally the same host name  as  might  happen  if
          sendmail  is  misconfigured or if a long-haul net-
          work interface is set in loopback mode.  This flag
          disables  the  loopback  check.  It should only be
          used under very unusual circumstances.

      K   Currently unimplemented.  Reserved for chunking.

      l   This mailer is local (i.e., final delivery will be
          performed).

      L   Limit  the  line  lengths as specified in RFC 821.
          This deprecated option should be replaced  by  the
          L=  mail declaration.  For historic reasons, the L
          flag also sets the 7 flag.

      m   This mailer can send to multiple users on the same
          host  in  one transaction.  When a $u macro occurs
          in the argv part of the  mailer  definition,  that
          field will be repeated as necessary for all quali-
          fying users.  Removing this flag can defeat dupli-
          cate  suppression on a remote site as each recipi-
          ent is sent in a separate transaction.

      M*  This mailer wants a "Message-Id:" header line.

      n   Do not insert a  UNIX-style  "From"  line  on  the
          front of the message.

      o   Always  run as the owner of the recipient mailbox.
          Normally sendmail runs as the sender  for  locally










SMM:08-92          Sendmail Installation and Operation Guide


          generated  mail or as "daemon" (actually, the user
          specified in the u option) when delivering network
          mail.  The normal behavior is required by most lo-
          cal mailers, which will  not  allow  the  envelope
          sender address to be set unless the mailer is run-
          ning as daemon.  This flag is  ignored  if  the  S
          flag is set.

      p   Use  the route-addr style reverse-path in the SMTP
          SMTP MAIL command rather than just the return  ad-
          dress;  although  this is required in RFC 821 sec-
          tion 3.1, many hosts do not process  reverse-paths
          properly.   Reverse-paths  are officially discour-
          aged by RFC 1123.

      P*  This mailer wants a "Return-Path:" line.

      q   When an address that resolves to  this  mailer  is
          verified  (SMTP  VRFY  command),  generate 250 re-
          sponses instead of 252 responses.  This will imply
          that the address is local.

      r   Same as f, but sends a -r flag.

      R   Open  SMTP  connections from a "secure" port.  Se-
          cure ports aren't (secure, that is) except on UNIX
          machines,  so  it  is  unclear that this adds any-
          thing.  sendmail must be running  as  root  to  be
          able to use this flag.

      s   Strip  quote  characters  (" and \) off of the ad-
          dress before calling the mailer.

      S   Don't reset the userid before calling the  mailer.
          This  would  be used in a secure environment where
          sendmail ran as root.  This could be used to avoid
          forged  addresses.  If the U= field is also speci-
          fied, this flag causes the effective user id to be
          set to that user.

      u   Upper  case  should be preserved in user names for
          this mailer.  Standards  require  preservation  of
          case  in  the  local part of addresses, except for
          those address for which your  system  accepts  re-
          sponsibility.   RFC  2142  provides a long list of
          addresses which should be  case  insensitive.   If
          you  use this flag, you may be violating RFC 2142.
          Note that postmaster is always treated as  a  case
          insensitive address regardless of this flag.

      U   This mailer wants UUCP-style "From" lines with the
          ugly "remote from <host>" on the end.











Sendmail Installation and Operation Guide          SMM:08-93


      w   The user must have a valid  account  on  this  ma-
          chine,  i.e.,  getpwnam must succeed.  If not, the
          mail is bounced.  See also the MailboxDatabase op-
          tion.  This is required to get ".forward" capabil-
          ity.

      W   Ignore long term host status information (see Sec-
          tion "Persistent Host Status Information").

      x*  This mailer wants a "Full-Name:" header line.

      X   This  mailer wants to use the hidden dot algorithm
          as specified in RFC 821; basically, any  line  be-
          ginning   with  a  dot  will  have  an  extra  dot
          prepended (to be stripped at the other end).  This
          insures that lines in the message containing a dot
          will not terminate the message prematurely.

      z   Run Local Mail Transfer  Protocol  (LMTP)  between
          sendmail  and the local mailer.  This is a variant
          on SMTP defined in RFC 2033 that  is  specifically
          designed for delivery to a local mailbox.

      Z   Apply DialDelay (if set) to this mailer.

      0   Don't  look  up  MX  records  for  hosts  sent via
          SMTP/LMTP.  Do not apply FallbackMXhost either.

      1   Don't send null characters ('\0') to this mailer.

      2   Don't use ESMTP even if offered;  this  is  useful
          for  broken  systems  that offer ESMTP but fail on
          EHLO (without recovering when HELO is tried next).

      3   Extend the list of characters converted to =XX no-
          tation  when converting to Quoted-Printable to in-
          clude those that don't map cleanly  between  ASCII
          and  EBCDIC.  Useful if you have IBM mainframes on
          site.

      5   If no aliases are found for this address, pass the
          address  through  ruleset 5 for possible alternate
          resolution.  This is intended to forward the  mail
          to an alternate delivery spot.

      6   Strip headers to seven bits.

      7   Strip  all  output to seven bits.  This is the de-
          fault if the L flag is set.   Note  that  clearing
          this  option  is  not sufficient to get full eight
          bit data passed through sendmail.  If the 7 option
          is  set, this is essentially always set, since the
          eighth bit was stripped on input.  Note that  this










SMM:08-94          Sendmail Installation and Operation Guide


          option  will only impact messages that didn't have
          8->7 bit MIME conversions performed.

      8   If set, it is acceptable to send eight bit data to
          this mailer; the usual attempt to do 8->7 bit MIME
          conversions will be bypassed.

      9   If set, do  limited  7->8  bit  MIME  conversions.
          These conversions are limited to text/plain data.

      :   Check  addresses to see if they begin ":include:";
          if  they  do,  convert  them  to  the  "*include*"
          mailer.

      |   Check  addresses  to see if they begin with a `|';
          if they do, convert them to the "prog" mailer.

      /   Check addresses to see if they begin with  a  `/';
          if they do, convert them to the "*file*" mailer.

      @   Look up addresses in the user database.

      %   Do  not  attempt  delivery on initial receipt of a
          message or on queue runs unless the queued message
          is selected using one of the -qI/-qR/-qS queue run
          modifiers or an ETRN request.

      !   Disable an MH hack that drops  an  explicit  From:
          header  if  it  is the same as what sendmail would
          generate.

           Configuration files prior to level 6  assume  the
      `A',  `w',  `5', `:', `|', `/', and `@' options on the
      mailer named "local".

           The mailer with the special name "error"  can  be
      used  to  generate  a user error.  The (optional) host
      field is an exit status to be returned, and  the  user
      field is a message to be printed.  The exit status may
      be numeric or one of the values USAGE, NOUSER, NOHOST,
      UNAVAILABLE,  SOFTWARE,  TEMPFAIL, PROTOCOL, or CONFIG
      to return the corresponding EX_ exit code, or  an  en-
      hanced  error  code as described in RFC 1893, Enhanced
      Mail System Status Codes.  For example, the entry:

          $#error $@ NOHOST $: Host unknown in this domain

      on the RHS of a rule will cause the specified error to
      be  generated and the "Host unknown" exit status to be
      returned if the LHS  matches.   This  mailer  is  only
      functional  in  rulesets  0,  5, or one of the check_*
      rulesets.  The host field can also contain the special
      token   quarantine   which   instructs   sendmail   to










Sendmail Installation and Operation Guide          SMM:08-95


      quarantine the current message.

           The mailer with the special name "discard" causes
      any  mail  sent  to  it  to be discarded but otherwise
      treated as  though  it  were  successfully  delivered.
      This  mailer  cannot be used in ruleset 0, only in the
      various address checking rulesets.

           The mailer named "local" must be defined in every
      configuration  file.   This  is  used to deliver local
      mail, and is treated specially in several ways.  Addi-
      tionally,  three other mailers named "prog", "*file*",
      and "*include*" may be defined to tune the delivery of
      messages  to  programs, files, and :include: lists re-
      spectively.  They default to:

          Mprog, P=/bin/sh, F=lsoDq9, T=DNS/RFC822/X-Unix, A=sh -c $u
          M*file*, P=[FILE], F=lsDFMPEouq9, T=DNS/RFC822/X-Unix, A=FILE $u
          M*include*, P=/dev/null, F=su, A=INCLUDE $u


           Builtin pathnames are [FILE] and [IPC], the  for-
      mer  is used for delivery to files, the latter for de-
      livery via interprocess  communication.   For  mailers
      that  use  [IPC]  as pathname the argument vector (A=)
      must start with TCP or FILE for delivery via a TCP  or
      a  Unix domain socket.  If TCP is used, the second ar-
      gument must be the name of the host to  contact.   Op-
      tionally  a  third  argument  can be used to specify a
      port, the default is smtp (port 25).  If FILE is used,
      the  second  argument must be the name of the Unix do-
      main socket.

           If the argument vector does not contain  $u  then
      sendmail will speak SMTP (or LMTP if the mailer flag z
      is specified) to the mailer.

           If no Eol field is defined, then the  default  is
      "\r\n" for SMTP mailers and "\n" of others.

           The  Sender  and Recipient rewriting sets may ei-
      ther be a simple ruleset id or may be  two  ids  sepa-
      rated  by  a  slash; if so, the first rewriting set is
      applied to envelope addresses and the  second  is  ap-
      plied  to headers.  Setting any value to zero disables
      corresponding mailer-specific rewriting.

           The Directory is actually a colon-separated  path
      of  directories  to  try.  For example, the definition
      "D=$z:/" first tries to  execute  in  the  recipient's
      home  directory; if that is not available, it tries to
      execute in the root of the filesystem.   This  is  in-
      tended  to  be  used  only on the "prog" mailer, since










SMM:08-96          Sendmail Installation and Operation Guide


      some shells (such as csh) refuse to  execute  if  they
      cannot  read  the  current directory.  Since the queue
      directory is not  normally  readable  by  unprivileged
      users csh scripts as recipients can fail.

           The  Userid  specifies the default user and group
      id  to  run  as,  overriding  the  DefaultUser  option
      (q.v.).   If the S mailer flag is also specified, this
      user and group will be set as the  effective  uid  and
      gid  for the process.  This may be given as user:group
      to set both the user and group id; either  may  be  an
      integer  or  a  symbolic  name  to be looked up in the
      passwd and group files respectively.  If only  a  sym-
      bolic  user  name  is  specified,  the group id in the
      passwd file for that user is used as the group id.

           The Charset field is used when converting a  mes-
      sage  to  MIME;  this is the character set used in the
      Content-Type: header.  If this is  not  set,  the  De-
      faultCharSet  option  is used, and if that is not set,
      the value "unknown-8bit" is used.  WARNING: this field
      applies  to  the  sender's mailer, not the recipient's
      mailer.  For example, if the envelope  sender  address
      lists  an address on the local network and the recipi-
      ent is on an external network, the character set  will
      be  set  from the Charset= field for the local network
      mailer, not that of the external network mailer.

           The Type= field sets the type information used in
      MIME error messages as defined by RFC 1894.  It is ac-
      tually three values separated by slashes: the MTA-type
      (that is, the description of how hosts are named), the
      address type (the description  of  e-mail  addresses),
      and  the diagnostic type (the description of error di-
      agnostic codes).  Each of these must be  a  registered
      value   or   begin   with   "X-".    The   default  is
      "dns/rfc822/smtp".

           The m= field specifies the maximum number of mes-
      sages  to  attempt to deliver on a single SMTP or LMTP
      connection.  The default is infinite.

           The r= field specifies the maximum number of  re-
      cipients  to  attempt to deliver in a single envelope.
      It defaults to 100.

           The /= field specifies a new root  directory  for
      the  mailer.   The  path  is  macro  expanded and then
      passed to the "chroot" system call.  The  root  direc-
      tory  is  changed  before  the Directory field is con-
      sulted or the uid is changed.












Sendmail Installation and Operation Guide          SMM:08-97


           The Wait= field specifies  the  maximum  time  to
      wait  for  the mailer to return after sending all data
      to it.  This applies to mailers that have been  forked
      by sendmail.

           The Queuegroup= field specifies the default queue
      group in which received mail should be  queued.   This
      can  be overridden by other means as explained in sec-
      tion ``Queue Groups and Queue Directories''.

   5.5.  H -- Define Header

           The format of the header lines that sendmail  in-
      serts into the message are defined by the H line.  The
      syntax of this line is one of the following:

          Hhname: htemplate


          H[?mflags?]hname: htemplate


          H[?${macro}?]hname: htemplate

      Continuation lines in this spec are reflected directly
      into the outgoing message.  The htemplate is macro-ex-
      panded before insertion  into  the  message.   If  the
      mflags  (surrounded  by question marks) are specified,
      at least one of the specified flags must be stated  in
      the  mailer definition for this header to be automati-
      cally output.  If a ${macro} (surrounded  by  question
      marks)  is specified, the header will be automatically
      output if the macro is set.  The macro may be set  us-
      ing  any  of  the  normal methods, including using the
      macro storage map in a ruleset.  If one of these head-
      ers  is in the input it is reflected to the output re-
      gardless of these  flags  or  macros.   Notice:  If  a
      ${macro} is used to set a header, then it is useful to
      add that macro  to  class  $={persistentMacros}  which
      consists  of  the  macros  that should be saved across
      queue runs.

           Some headers have special semantics that will  be
      described later.

           A  secondary  syntax allows validation of headers
      as they are being read.  To enable validation, use:

          HHeader: $>Ruleset
          HHeader: $>+Ruleset

      The indicated Ruleset  is  called  for  the  specified
      Header, and can return $#error to reject or quarantine










SMM:08-98          Sendmail Installation and Operation Guide


      the message or $#discard to discard  the  message  (as
      with  the  other  check_*  rulesets).  The ruleset re-
      ceives the header field-body as  argument,  i.e.,  not
      the header field-name; see also ${hdr_name} and ${cur-
      rHeader}.  The  header  is  treated  as  a  structured
      field,  that is, text in parentheses is deleted before
      processing, unless the second form $>+ is used.  Note:
      only  one  ruleset  can  be  associated with a header;
      sendmail will silently ignore multiple entries.

           For example, the configuration lines:

          HMessage-Id: $>CheckMessageId

          SCheckMessageId
          R< $+ @ $+  >$@ OK
          R$*       $#error $: Illegal Message-Id header

      would refuse any message that had a Message-Id: header
      of any of the following forms:

          Message-Id: <>
          Message-Id: some text
          Message-Id: <legal text@domain> extra crud

      A  default  ruleset  that  is called for headers which
      don't have a specific ruleset defined for them can  be
      specified by:

          H*: $>Ruleset

      or

          H*: $>+Ruleset


   5.6.  O -- Set Option

           There  are a number of global options that can be
      set from a configuration  file.   Options  are  repre-
      sented  by  full words; some are also representable as
      single characters for back compatibility.  The  syntax
      of this line is:

          O  option=value

      This  sets option option to be value.  Note that there
      must be a space between the letter `O' and the name of
      the option.  An older version is:

          Oovalue

      where  the  option o is a single character.  Depending










Sendmail Installation and Operation Guide          SMM:08-99


      on the option, value may be a string,  an  integer,  a
      boolean  (with legal values "t", "T", "f", or "F"; the
      default is TRUE), or a time interval.

           All filenames used in options should be  absolute
      paths,  i.e.,  starting  with '/'.  Relative filenames
      most likely cause surprises during  operation  (unless
      otherwise noted).

           The  options supported (with the old, one charac-
      ter names in brackets) are:

      AliasFile=spec, spec, ...
                [A] Specify possible  alias  file(s).   Each
                spec should be in the format ``class: info''
                where class: is  optional  and  defaults  to
                ``implicit''.   Note  that  info is required
                for all  classes  except  "ldap".   For  the
                "ldap"  class,  if  info is not specified, a
                default info value is used as follows:

                    -k (&(objectClass=sendmailMTAAliasObject)
                         (sendmailMTAAliasName=aliases)
                         (|(sendmailMTACluster=${sendmailMTACluster})
                           (sendmailMTAHost=$j))
                         (sendmailMTAKey=%0))
                    -v sendmailMTAAliasValue

                Depending on how sendmail is compiled, valid
                classes  are  "implicit"  (search  through a
                compiled-in list of alias  file  types,  for
                back  compatibility),  "hash"  (if  NEWDB is
                specified), "btree" (if NEWDB is specified),
                "dbm"  (if NDBM is specified), "cdb" (if CDB
                is specified), "stab" (internal symbol table
                --  not  normally  used  unless  you have no
                other database lookup),  "sequence"  (use  a
                sequence   of   maps  previously  declared),
                "ldap" (if LDAPMAP is specified),  or  "nis"
                (if  NIS  is specified).  If a list of specs
                are provided, sendmail searches them in  or-
                der.

      AliasWait=timeout
                [a]  If  set,  wait up to timeout (units de-
                fault to minutes) for an "@:@" entry to  ex-
                ist  in  the  alias database before starting
                up.  If it does not appear  in  the  timeout
                interval issue a warning.

      AllowBogusHELO
                [no short name] If set, allow HELO SMTP com-
                mands  that  don't  include  a  host   name.










SMM:08-100         Sendmail Installation and Operation Guide


                Setting   this  violates  RFC  1123  section
                5.2.5, but is necessary to interoperate with
                several  SMTP clients.  If there is a value,
                it is still checked for legitimacy.

      AuthMaxBits=N
                [no short name] Limit the maximum encryption
                strength for the security layer in SMTP AUTH
                (SASL). Default  is  essentially  unlimited.
                This  allows  to turn off additional encryp-
                tion in SASL if STARTTLS is already encrypt-
                ing  the communication, because the existing
                encryption strength is  taken  into  account
                when  choosing an algorithm for the security
                layer.  For example, if STARTTLS is used and
                the  symmetric  cipher  is  3DES,  then  the
                keylength (in bits) is 168.   Hence  setting
                AuthMaxBits  to 168 will disable any encryp-
                tion in SASL.

      AuthMechanisms
                [no short name] List of authentication mech-
                anisms  for AUTH (separated by spaces).  The
                advertised list of authentication mechanisms
                will  be  the  intersection of this list and
                the list of available mechanisms  as  deter-
                mined  by the Cyrus SASL library.  If START-
                TLS is active, EXTERNAL  will  be  added  to
                this  list.   In  that  case,  the  value of
                {cert_subject} is used as authentication id.

      AuthOptions
                [no short name] List  of  options  for  SMTP
                AUTH  consisting  of  single characters with
                intervening white space or commas.




























Sendmail Installation and Operation Guide         SMM:08-101


                    A   Use the AUTH= parameter for the MAIL
                        command only when authentication succeeded.
                        This can be used as a workaround for broken
                        MTAs that do not implement RFC 2554 correctly.
                    a   protection from active (non-dictionary) attacks
                        during authentication exchange.
                    c   require mechanisms which pass client credentials,
                        and allow mechanisms which can pass credentials
                        to do so.
                    d   don't permit mechanisms susceptible to passive
                        dictionary attack.
                    f   require forward secrecy between sessions
                        (breaking one won't help break next).
                    m   require mechanisms which provide mutual authentication
                        (only available if using Cyrus SASL v2 or later).
                    p   don't permit mechanisms susceptible to simple
                        passive attack (e.g., PLAIN, LOGIN), unless a
                        security layer is active.
                    y   don't permit mechanisms that allow anonymous login.

                The first option applies to  sendmail  as  a
                client, the others to a server.  Example:

                    O AuthOptions=p,y

                would  disallow  ANONYMOUS as AUTH mechanism
                and would allow PLAIN and LOGIN  only  if  a
                security  layer (e.g., provided by STARTTLS)
                is already active.  The  options  'a',  'c',
                'd',  'f',  'p', and 'y' refer to properties
                of the selected SASL  mechanisms.   Explana-
                tions  of  these  properties can be found in
                the Cyrus SASL documentation.

      AuthRealm [no short  name]  The  authentication  realm
                that  is  passed  to the Cyrus SASL library.
                If no realm is specified, $j is  used.   See
                also KNOWNBUGS.

      BadRcptThrottle=N
                [no  short  name]  If  set and the specified
                number of recipients in a single SMTP trans-
                action  have  been  rejected,  sleep for one
                second after each subsequent RCPT command in
                that transaction.

      BlankSub=c
                [B]  Set the blank substitution character to
                c.  Unquoted spaces  in  addresses  are  re-
                placed by this character.  Defaults to space
                (i.e., no change is made).












SMM:08-102         Sendmail Installation and Operation Guide


      CACertPath
                [no short name] Path to directory with  cer-
                tificates  of CAs.  This directory directory
                must contain the hashes of each CA  certifi-
                cate as filenames (or as links to them).

      CACertFile
                [no  short name] File containing one or more
                CA certificates; see section about  STARTTLS
                for more information.

      CertFingerprintAlgorithm
                Specify  the  fingerprint algorithm (digest)
                to use for the presented cert.  If  the  op-
                tion  is  not set, md5 is used and the macro
                ${cert_md5} contains the  cert  fingerprint.
                If  the option is explicitly set, the speci-
                fied algorithm (e.g., sha1) is used and  the
                macro  ${cert_fp}  contains the cert finger-
                print.

      CipherList
                Specify cipher list for STARTTLS  (does  not
                apply  to TLSv1.3).  See ciphers(1) for pos-
                sible values.

      CheckAliases
                [n] Validate the RHS  of  aliases  when  re-
                building the alias database.

      CheckpointInterval=N
                [C]  Checkpoints  the queue every N (default
                10) addresses sent.  If your system  crashes
                during  delivery  to a large list, this pre-
                vents retransmission to any but the  last  N
                recipients.

      ClassFactor=fact
                [z]  The  indicated  factor is multiplied by
                the message class (determined by the  Prece-
                dence:  field  in  the user header and the P
                lines in the configuration  file)  and  sub-
                tracted  from  the priority.  Thus, messages
                with a higher  Priority:  will  be  favored.
                Defaults to 1800.

      ClientCertFile
                [no short name] File containing the certifi-
                cate of the client, i.e.,  this  certificate
                is  used  when  sendmail acts as client (for
                STARTTLS).












Sendmail Installation and Operation Guide         SMM:08-103


      ClientKeyFile
                [no short name] File containing the  private
                key belonging to the client certificate (for
                STARTTLS if sendmail runs as client).

      ClientPortOptions=options
                [no short name]  Set  client  SMTP  options.
                The options are key=value pairs separated by
                commas.  Known keys are:

                    Port      Name/number of source port for connection (defaults to any free port)
                    Addr      Address mask (defaults INADDR_ANY)
                    Family    Address family (defaults to INET)
                    SndBufSizeSize of TCP send buffer
                    RcvBufSizeSize of TCP receive buffer
                    Modifier  Options (flags) for the client

                The Address mask may be a numeric address in
                IPv4  dot notation or IPv6 colon notation or
                a network name.  Note that if a network name
                is  specified, only the first IP address re-
                turned for it will be used.  This may  cause
                indeterminate  behavior  for  network  names
                that resolve to multiple addresses.   There-
                fore,  use  of  an  address  is recommended.
                Modifier can be the following character:

                    h         use name of interface for HELO command
                    A         don't use AUTH when sending e-mail
                    S         don't use STARTTLS when sending e-mail

                If ``h'' is set, the name  corresponding  to
                the outgoing interface address (whether cho-
                sen via the Connection parameter or the  de-
                fault)  is  used  for the HELO/EHLO command.
                However, the name  must  not  start  with  a
                square  bracket and it must contain at least
                one dot.  This is a simple test whether  the
                name  is not an IP address (in square brack-
                ets) but a qualified  hostname.   Note  that
                multiple  ClientPortOptions settings are al-
                lowed in order to  give  settings  for  each
                protocol  family  (e.g., one for Family=inet
                and one for  Family=inet6).   A  restriction
                placed  on  one family only affects outgoing
                connections on that particular family.

      ClientSSLOptions
                A space or comma separated list of  SSL  re-
                lated  options  for  the  client  side.  See
                SSL_CTX_set_options(3)  for  a   list;   the
                available  values depend on the OpenSSL ver-
                sion against which sendmail is compiled.  By










SMM:08-104         Sendmail Installation and Operation Guide


                default,      SSL_OP_ALL     SSL_OP_NO_SSLv2
                SSL_OP_NO_TICKET -SSL_OP_TLSEXT_PADDING  are
                used  (if those options are available).  Op-
                tions can be cleared by preceding them  with
                a  minus sign.  It is also possible to spec-
                ify numerical values, e.g., -0x0010.

      ColonOkInAddr
                [no short name] If set, colons  are  accept-
                able     in    e-mail    addresses    (e.g.,
                "host:user").  If not set,  colons  indicate
                the  beginning  of a RFC 822 group construct
                ("groupname:  member1,  member2,  ...   mem-
                berN;").   Doubled colons are always accept-
                able ("nodename::user")  and  proper  route-
                addr    nesting    is   understood   ("<@re-
                lay:user@host>").  Furthermore, this  option
                defaults  on  if  the  configuration version
                level is less than 6 (for  back  compatibil-
                ity).  However, it must be off for full com-
                patibility with RFC 822.

      ConnectionCacheSize=N
                [k] The maximum number of  open  connections
                that  will be cached at a time.  The default
                is one.  This  delays  closing  the  current
                connection  until  either this invocation of
                sendmail needs to connect to another host or
                it  terminates.  Setting it to zero defaults
                to the old behavior,  that  is,  connections
                are closed immediately.  Since this consumes
                file  descriptors,  the   connection   cache
                should  be kept small: 4 is probably a prac-
                tical maximum.

      ConnectionCacheTimeout=timeout
                [K] The maximum amount of time a cached con-
                nection  will  be  permitted to idle without
                activity.  If this  time  is  exceeded,  the
                connection   is  immediately  closed.   This
                value should be small (on the order  of  ten
                minutes).   Before  sendmail  uses  a cached
                connection, it always sends a  RSET  command
                to  check  the connection; if this fails, it
                reopens the connection.  This keeps your end
                from  failing  if  the  other end times out.
                The point of this option is  to  be  a  good
                network  neighbor  and avoid using up exces-
                sive resources on the other  end.   The  de-
                fault is five minutes.

      ConnectOnlyTo=address
                [no short name] This can be used to override










Sendmail Installation and Operation Guide         SMM:08-105


                the connection  address  (for  testing  pur-
                poses).

      ConnectionRateThrottle=N
                [no  short name] If set to a positive value,
                allow no more than N incoming connections in
                a one second period per daemon.  This is in-
                tended to flatten out peaks  and  allow  the
                load  average  checking to cut in.  Defaults
                to zero (no limits).

      ConnectionRateWindowSize=N
                [no short name] Define the length of the in-
                terval for which the number of incoming con-
                nections is maintained.  The default  is  60
                seconds.

      ControlSocketName=name
                [no  short  name] Name of the control socket
                for daemon management.  A  running  sendmail
                daemon  can be controlled through this named
                socket.   Available  commands   are:   help,
                mstat,  restart,  shutdown, and status.  The
                status command returns the current number of
                daemon  children, the maximum number of dae-
                mon  children,  the  free  disk  space   (in
                blocks) of the queue directory, and the load
                average of the machine expressed as an inte-
                ger.   If not set, no control socket will be
                available.  Solaris  and  pre-4.4BSD  kernel
                users should see the note in sendmail/README
                .

      CRLFile=name
                [no short name] Name of file  that  contains
                certificate  revocation  status,  useful for
                X.509v3 authentication.  Note: if a  CRLFile
                is  specified  but  the  file  is  unusable,
                STARTTLS is disabled.

      CRLPath=name
                [no short name] Name of directory that  con-
                tains hashes pointing to certificate revoca-
                tion status files.  Symbolic  links  can  be
                generated  with  the  following two (Bourne)
                shell commands:

                    C=FileName_of_CRL
                    ln -s $C `openssl crl -noout -hash < $C`.r0


      DHParameters
                This option applies to the server side only.










SMM:08-106         Sendmail Installation and Operation Guide


                Possible values are:

                    5                   use precomputed 512 bit prime.
                    1                   generate 1024 bit prime
                    2                   generate 2048 bit prime.
                    i                   use included precomputed 2048 bit prime (default).
                    none                do not use Diffie-Hellman.
                    /path/to/file       load prime from file.

                This  is only required if a ciphersuite con-
                taining DSA/DH  is  used.   The  default  is
                ``i''  which  selects  a  precomputed, fixed
                2048 bit prime.  If ``5'' is selected,  then
                precomputed,  fixed  primes are used.  Note:
                this option should not be used (unless  nec-
                essary  for compatibility with old implemen-
                tations).  If ``1'' or  ``2''  is  selected,
                then   prime   values  are  computed  during
                startup.  Note: this operation  can  take  a
                significant amount of time on a slow machine
                (several seconds), but it is only done  once
                at  startup.   If ``none'' is selected, then
                TLS ciphersuites containing DSA/DH cannot be
                used.   If  a  file name is specified (which
                must be an absolute path), then  the  primes
                are read from it.  It is recommended to gen-
                erate such a file using a command like this:

                                        openssl dhparam -out /etc/mail/dhparams.pem 2048

                If the file is not readable or contains  un-
                usable  data,  the default ``i'' is used in-
                stead.

      DaemonPortOptions=options
                [O] Set server SMTP options.  Each  instance
                of  DaemonPortOptions leads to an additional
                incoming socket.  The options are  key=value
                pairs.  Known keys are:
























Sendmail Installation and Operation Guide         SMM:08-107


                    Name      User-definable name for the daemon (defaults to "Daemon#")
                    Port      Name/number of listening port (defaults to "smtp")
                    Addr      Address mask (defaults INADDR_ANY)
                    Family    Address family (defaults to INET)
                    InputMailFiltersList of input mail filters for the daemon
                    Listen    Size of listen queue (defaults to 10)
                    Modifier  Options (flags) for the daemon
                    SndBufSizeSize of TCP send buffer
                    RcvBufSizeSize of TCP receive buffer
                    children  maximum number of children per daemon, see MaxDaemonChildren.
                    DeliveryModeDelivery mode per daemon, see DeliveryMode.
                    refuseLA  RefuseLA per daemon
                    delayLA   DelayLA per daemon
                    queueLA   QueueLA per daemon

                The  Name key is used for error messages and
                logging.  The Address mask may be a  numeric
                address  in  IPv4 dot notation or IPv6 colon
                notation, or a network name, or a path to  a
                local  socket.   Note that if a network name
                is specified, only the first IP address  re-
                turned  for it will be used.  This may cause
                indeterminate  behavior  for  network  names
                that  resolve to multiple addresses.  There-
                fore, use of an address is recommended.  The
                Family  key  defaults  to INET (IPv4).  IPv6
                users who wish to also accept  IPv6  connec-
                tions  should  add  additional  Family=inet6
                DaemonPortOptions  lines.    For   a   local
                socket,  use  Family=local  or  Family=unix.
                The InputMailFilters key overrides  the  de-
                fault  list  of input mail filters listed in
                the InputMailFilters  option.   If  multiple
                input  mail  filters are required, they must
                be separated  by  semicolons  (not  commas).
                Modifier  can be a sequence (without any de-
                limiters) of the following characters:

                    a         always require AUTH
                    b         bind to interface through which mail has been received
                    c         perform hostname canonification (.cf)
                    f         require fully qualified hostname (.cf)
                    s         Run smtps (SMTP over SSL) instead of smtp
                    u         allow unqualified addresses (.cf)
                    A         disable AUTH (overrides 'a' modifier)
                    C         don't perform hostname canonification
                    E         disallow ETRN (see RFC 2476)
                    O         optional; if opening the socket fails ignore it
                    S         don't offer STARTTLS

                That is, one way to specify a  message  sub-
                mission  agent  (MSA)  that  always requires
                AUTH is:










SMM:08-108         Sendmail Installation and Operation Guide


                    O DaemonPortOptions=Name=MSA, Port=587, M=Ea

                The modifiers that are marked  with  "(.cf)"
                have  only effect in the standard configura-
                tion file, in which they are  available  via
                ${daemon_flags}.   Notice:  Do  not  use the
                ``a'' modifier on a public  accessible  MTA!
                It should only be used for a MSA that is ac-
                cessed by authorized users for initial  mail
                submission.   Users must authenticate to use
                a MSA which has this option turned on.   The
                flags ``c'' and ``C'' can change the default
                for hostname  canonification  in  the  send-
                mail.cf  file.   See the relevant documenta-
                tion for FEATURE(nocanonify).  The  modifier
                ``f''   disallows   addresses  of  the  form
                user@host  unless  they  are  submitted  di-
                rectly.   The  flag ``u'' allows unqualified
                sender addresses, i.e., those without @host.
                ``b''  forces sendmail to bind to the inter-
                face through which the e-mail has  been  re-
                ceived  for  the outgoing connection.  WARN-
                ING: Use ``b'' only if outgoing mail can  be
                routed through the incoming connection's in-
                terface to its destination.  No  attempt  is
                made  to catch problems due to a misconfigu-
                ration of this parameter, use  it  only  for
                virtual hosting where each virtual interface
                can  connect  to  every  possible  location.
                This  will  also  override possible settings
                via ClientPortOptions.  Note, sendmail  will
                listen  on  a new socket for each occurrence
                of the DaemonPortOptions option in a config-
                uration  file.   The  modifier  ``O'' causes
                sendmail to ignore a socket if it  can't  be
                opened.   This  applies to failures from the
                socket(2) and bind(2) calls.

      DefaultAuthInfo
                [no short name] Filename that  contains  de-
                fault  authentication information for outgo-
                ing connections. This file must contain  the
                user  id, the authorization id, the password
                (plain text), the  realm  and  the  list  of
                mechanisms to use on separate lines and must
                be readable by root (or  the  trusted  user)
                only.  If no realm is specified, $j is used.
                If no mechanisms  are  specified,  the  list
                given  by  AuthMechanisms  is used.  Notice:
                this option is deprecated and  will  be  re-
                moved  in  future  versions.   Moreover,  it
                doesn't work for the MSP since it can't read
                the  file (the file must not be group/world-










Sendmail Installation and Operation Guide         SMM:08-109


                readable otherwise sendmail will  complain).
                Use  the authinfo ruleset instead which pro-
                vides more control over  the  usage  of  the
                data anyway.

      DefaultCharSet=charset
                [no  short  name]  When  a  message that has
                8-bit characters but is not in  MIME  format
                is  converted  to MIME (see the EightBitMode
                option) a character set must be included  in
                the  Content-Type:  header.   This character
                set is normally set from the Charset=  field
                of  the  mailer  descriptor.  If that is not
                set, the value of this option is  used.   If
                this  option  is  not  set,  the  value "un-
                known-8bit" is used.

      DataFileBufferSize=threshold
                [no short name] Set the threshold, in bytes,
                before  a  memory-based  queue data file be-
                comes  disk-based.   The  default  is   4096
                bytes.

      DeadLetterDrop=file
                [no  short name] Defines the location of the
                system-wide dead.letter file, formerly hard-
                coded  to /usr/tmp/dead.letter.  If this op-
                tion is not set (the default), sendmail will
                not   attempt   to  save  to  a  system-wide
                dead.letter file  in  the  event  it  cannot
                bounce  the  mail to the user or postmaster.
                Instead, it will rename the qf  file  as  it
                has  in  the  past when the dead.letter file
                could not be opened.

      DefaultUser=user:group
                [u] Set the default userid  for  mailers  to
                user:group.  If group is omitted and user is
                a user name (as opposed to  a  numeric  user
                id)   the   default   group  listed  in  the
                /etc/passwd file for that user  is  used  as
                the  default group.  Both user and group may
                be numeric.  Mailers without the S  flag  in
                the mailer definition will run as this user.
                Defaults to 1:1.   The  value  can  also  be
                given as a symbolic user name.[19]


____________________
   [19]The  old g option has been combined into the Default-
User option.












SMM:08-110         Sendmail Installation and Operation Guide


      DelayLA=LA
                [no short name] When the system load average
                exceeds LA, sendmail will sleep for one sec-
                ond on most SMTP commands and before accept-
                ing connections.

      DeliverByMin=time
                [no short name] Set minimum time for Deliver
                By SMTP Service Extension (RFC 2852).  If 0,
                no  time  is listed, if less than 0, the ex-
                tension is not offered, if greater  than  0,
                it  is  listed  as minimum time for the EHLO
                keyword DELIVERBY.

      DeliveryMode=x
                [d] Deliver in mode x.  Legal modes are:

                    i   Deliver interactively (synchronously)
                    b   Deliver in background (asynchronously)
                    q   Just queue the message (deliver during queue run)
                    d   Defer delivery and all map lookups (deliver during queue run)

                Defaults to ``b'' if no option is specified,
                ``i''  if it is specified but given no argu-
                ment  (i.e.,   ``Od''   is   equivalent   to
                ``Odi'').   The  -v  command  line flag sets
                this to  i.   Note:  for  internal  reasons,
                ``i''  does  not work if a milter is enabled
                which can reject or delete  recipients.   In
                that case the mode will be changed to ``b''.

      DialDelay=sleeptime
                [no  short name] Dial-on-demand network con-
                nections can see timeouts if a connection is
                opened  before  the call is set up.  If this
                is set to an interval and a connection times
                out  on the first connection being attempted
                sendmail will sleep for this amount of  time
                and try again.  This should give your system
                time to establish  the  connection  to  your
                service provider.  Units default to seconds,
                so "DialDelay=5" uses a five  second  delay.
                Defaults  to  zero  (no  retry).  This delay
                only applies to mailers  which  have  the  Z
                flag set.

      DirectSubmissionModifiers=modifiers
                Defines  ${daemon_flags} for direct (command
                line)  submissions.   If  not  set,   ${dae-
                mon_flags} is either "CC f" if the option -G
                is used or "c u" otherwise.  Note that  only
                the  "CC",  "c",  "f",  and  "u"  flags  are
                checked.










Sendmail Installation and Operation Guide         SMM:08-111


      DontBlameSendmail=option,option,...
                [no short name] In order to  avoid  possible
                cracking   attempts  caused  by  world-  and
                group-writable files and directories,  send-
                mail  does  paranoid  checking  when opening
                most of its support files.  If for some rea-
                son  you absolutely must run with, for exam-
                ple, a group-writable /etc  directory,  then
                you  will have to turn off this checking (at
                the cost of making your system more vulnera-
                ble to attack).  The possible arguments have
                been  described  earlier.   The  details  of
                these  flags  are  described  above.  Use of
                this option is not recommended.

      DontExpandCnames
                [no short name] The standards say  that  all
                host  addresses  used in a mail message must
                be fully canonical.  For  example,  if  your
                host  is  named "Cruft.Foo.ORG" and also has
                an alias of "FTP.Foo.ORG", the  former  name
                must be used at all times.  This is enforced
                during host name canonification ($[  ...  $]
                lookups).  If this option is set, the proto-
                cols are ignored and the  "wrong"  thing  is
                done.   However,  the  IETF is moving toward
                changing this standard, so the behavior  may
                become  acceptable.   Please note that hosts
                downstream may still rewrite the address  to
                be the true canonical name however.

      DontInitGroups
                [no  short name] If set, sendmail will avoid
                using the initgroups(3) call.   If  you  are
                running  NIS,  this causes a sequential scan
                of the groups.byname map,  which  can  cause
                your  NIS server to be badly overloaded in a
                large domain.  The cost of this is that  the
                only  group  found  for  users will be their
                primary  group  (the  one  in  the  password
                file),  which  will make file access permis-
                sions somewhat more restrictive.  Has no ef-
                fect on systems that don't have group lists.

      DontProbeInterfaces
                [no  short name] Sendmail normally finds the
                names of all interfaces active on  your  ma-
                chine  when it starts up and adds their name
                to the $=w class of known host aliases.   If
                you  have  a  large number of virtual inter-
                faces or if your  DNS  inverse  lookups  are
                slow  this  can be time consuming.  This op-
                tion turns off that probing.   However,  you










SMM:08-112         Sendmail Installation and Operation Guide


                will need to be certain to include all vari-
                ant names in the $=w  class  by  some  other
                mechanism.  If set to loopback, loopback in-
                terfaces (e.g., lo0) will not be probed.

      DontPruneRoutes
                [R] Normally, sendmail  tries  to  eliminate
                any unnecessary explicit routes when sending
                an error message (as discussed in RFC 1123 S
                5.2.6).   For example, when sending an error
                message to

                    <@known1,@known2,@known3:user@unknown>

                sendmail     will     strip     off      the
                "@known1,@known2" in order to make the route
                as direct as possible.  However,  if  the  R
                option  is  set,  this will be disabled, and
                the mail will be sent to the  first  address
                in  the  route,  even if later addresses are
                known.  This may be useful if you are caught
                behind a firewall.

      DoubleBounceAddress=error-address
                [no  short  name]  If  an  error occurs when
                sending an error message, send the error re-
                port (termed a "double bounce" because it is
                an error "bounce" that occurs when trying to
                send  another  error  "bounce") to the indi-
                cated address.  The  address  is  macro  ex-
                panded at the time of delivery.  If not set,
                defaults to  "postmaster".   If  set  to  an
                empty string, double bounces are dropped.

      EightBitMode=action
                [8]  Set  handling of eight-bit data.  There
                are two kinds of eight-bit  data:  that  de-
                clared as such using the BODY=8BITMIME ESMTP
                declaration or the -B8BITMIME  command  line
                flag,  and  undeclared  8-bit data, that is,
                input that just happens to  be  eight  bits.
                There  are  three  basic operations that can
                happen: undeclared 8-bit data can  be  auto-
                matically  converted to 8BITMIME, undeclared
                8-bit data can be passed as-is without  con-
                version  to  MIME (``just send 8''), and de-
                clared 8-bit data can be converted to 7-bits
                for  transmission  to a non-8BITMIME mailer.
                The possible actions are:

                      s Reject undeclared 8-bit data (``strict'')
                      m Convert undeclared 8-bit data to MIME (``mime'')
                      p Pass undeclared 8-bit data (``pass'')










Sendmail Installation and Operation Guide         SMM:08-113


                In all cases properly declared 8BITMIME data
                will  be converted to 7BIT as needed.  Note:
                if an automatic conversion is  performed,  a
                header  with  the  following  format will be
                added:

                    X-MIME-Autoconverted: from OLD to NEW by $j id $i

                where OLD and NEW describe the original for-
                mat and the converted format, respectively.

      ErrorHeader=file-or-message
                [E]  Prepend  error  messages with the indi-
                cated message.  If it begins with  a  slash,
                it  is  assumed to be the pathname of a file
                containing a message  (this  is  the  recom-
                mended setting).  Otherwise, it is a literal
                message.  The error file might  contain  the
                name,  email address, and/or phone number of
                a local postmaster who could provide assist-
                ance to end users.  If the option is missing
                or null, or if it names a  file  which  does
                not  exist or which is not readable, no mes-
                sage is printed.

      ErrorMode=x
                [e] Dispose of errors  using  mode  x.   The
                values for x are:

                    p   Print error messages (default)
                    q   No messages, just give exit status
                    m   Mail back errors
                    w   Write back errors (mail if user not logged in)
                    e   Mail back errors (when applicable) and give zero exit stat always

                Note that the last mode, "e", is for Berknet
                error processing and should not be  used  in
                normal  circumstances.  Note, too, that mode
                "q", only applies to errors  recognized  be-
                fore sendmail forks for background delivery.

      FallbackMXhost=fallbackhost
                [V] If specified, the fallbackhost acts like
                a very low priority MX on  every  host.   MX
                records will be looked up for this host, un-
                less the name is surrounded by square brack-
                ets.   This  is intended to be used by sites
                with poor  network  connectivity.   Messages
                which are undeliverable due to temporary ad-
                dress failures (e.g., DNS failure)  also  go
                to the FallbackMXhost.












SMM:08-114         Sendmail Installation and Operation Guide


      FallBackSmartHost=hostname
                If  specified, the FallBackSmartHost will be
                used in a last-ditch effort for  each  host.
                This  is  intended  to be used by sites with
                "fake internal DNS", e.g., a  company  whose
                DNS  accurately  reflects  the  world inside
                that company's domain but not outside.

      FastSplit [no short name] If set to  a  value  greater
                than  zero  (the  default  is  one), it sup-
                presses the MX  lookups  on  addresses  when
                they  are  initially  sorted,  i.e., for the
                first delivery attempt.   This  usually  re-
                sults  in  faster  envelope splitting unless
                the MX records are readily  available  in  a
                local DNS cache.  To enforce initial sorting
                based on MX records set FastSplit  to  zero.
                If  the  mail is submitted directly from the
                command line, then the value also limits the
                number  of  processes  to  deliver  the  en-
                velopes; if more envelopes are created  they
                are only queued up and must be taken care of
                by a queue run.  Since the  default  submis-
                sion  method  is via SMTP (either from a MUA
                or via the MSP), the value of  FastSplit  is
                seldom used to limit the number of processes
                to deliver the envelopes.

      ForkEachJob
                [Y] If set, deliver each  job  that  is  run
                from the queue in a separate process.

      ForwardPath=path
                [J]  Set  the  path for searching for users'
                .forward files.  The  default  is  "$z/.for-
                ward".   Some sites that use the automounter
                may prefer  to  change  this  to  "/var/for-
                ward/$u" to search a file with the same name
                as the user in a system directory.   It  can
                also be set to a sequence of paths separated
                by colons; sendmail stops at the first  file
                it  can  successfully  and safely open.  For
                example, "/var/forward/$u:$z/.forward"  will
                search  first  in  /var/forward/username and
                then in ~username/.forward (but only if  the
                first file does not exist).

      HeloName=name
                [no  short name] Set the name to be used for
                HELO/EHLO (instead of $j).

      HelpFile=file
                [H] Specify the help file for SMTP.   If  no










Sendmail Installation and Operation Guide         SMM:08-115


                file  name is specified, "helpfile" is used.
                If the help file does not exist  (cannot  be
                opened  for  reading)  sendmail will print a
                note including its version in response to  a
                HELP  command.   To avoid providing this in-
                formation to a client specify an empty file.

      HoldExpensive
                [c] If an outgoing mailer is marked as being
                expensive, don't connect immediately.

      HostsFile=path
                [no  short name] The path to the hosts data-
                base, normally "/etc/hosts".  This option is
                only  consulted when sendmail is canonifying
                addresses, and then only when "files" is  in
                the  "hosts"  service switch entry.  In par-
                ticular, this file is never used when  look-
                ing  up  host  addresses;  that is under the
                control of the system gethostbyname(3)  rou-
                tine.

      HostStatusDirectory=path
                [no  short  name]  The  location of the long
                term host status information.  When set, in-
                formation  about  the status of hosts (e.g.,
                host down or not accepting connections) will
                be  shared  between  all sendmail processes;
                normally,  this  information  is  only  held
                within  a single queue run.  This option re-
                quires a connection cache of at least  1  to
                function.  If the option begins with a lead-
                ing `/', it is an absolute pathname;  other-
                wise,  it  is relative to the mail queue di-
                rectory.  A suggested value for sites desir-
                ing  persistent  host  status is ".hoststat"
                (i.e., a subdirectory of  the  queue  direc-
                tory).

      IgnoreDots
                [i]  Ignore dots in incoming messages.  This
                is always disabled (that is, dots are always
                accepted) when reading SMTP mail.

      InputMailFilters=name,name,...
                A  comma separated list of filters which de-
                termines which filters (see the "X  --  Mail
                Filter  (Milter)  Definitions"  section) and
                the invocation sequence  are  contacted  for
                incoming SMTP messages.  If none are set, no
                filters will be contacted.












SMM:08-116         Sendmail Installation and Operation Guide


      LDAPDefaultSpec=spec
                [no short name] Sets a default map  specifi-
                cation for LDAP maps.  The value should only
                contain LDAP specific settings such  as  "-h
                host  -p port -d bindDN".  The settings will
                be used for all LDAP maps unless  the  indi-
                vidual  map  specification  overrides a set-
                ting.  This option should be set before  any
                LDAP maps are defined.

      LogLevel=n
                [L] Set the log level to n.  Defaults to 9.

      Mxvalue   [no  long version] Set the macro x to value.
                This is intended only for use from the  com-
                mand line.  The -M flag is preferred.

      MailboxDatabase
                [no  short  name] Type of lookup to find in-
                formation about local mailboxes, defaults to
                ``pw'' which uses getpwnam.  Other types can
                be introduced by adding them to  the  source
                code, see libsm/mbdb.c for details.

      UseMSP    [no  short name] Use as mail submission pro-
                gram, i.e., allow group writable queue files
                if  the  group is the same as that of a set-
                group-ID  sendmail  binary.   See  the  file
                sendmail/SECURITY  in  the distribution tar-
                ball.

      MatchGECOS
                [G] Allow fuzzy matching on the GECOS field.
                If this flag is set, and the usual user name
                lookups fail (that is,  there  is  no  alias
                with  this  name  and a getpwnam fails), se-
                quentially search the password  file  for  a
                matching  entry  in  the  GECOS field.  This
                also requires that MATCHGECOS be  turned  on
                during compilation.  This option is not rec-
                ommended.

      MaxAliasRecursion=N
                [no short name] The maximum depth  of  alias
                recursion (default: 10).

      MaxDaemonChildren=N
                [no short name] If set, sendmail will refuse
                connections when it has more than N children
                processing  incoming mail or automatic queue
                runs.  This does not  limit  the  number  of
                outgoing connections.  If the default Deliv-
                eryMode (background) is used, then  sendmail










Sendmail Installation and Operation Guide         SMM:08-117


                may  create  an  almost  unlimited number of
                children (depending on the number of  trans-
                actions  and the relative execution times of
                mail receiption and mail delivery).  If  the
                limit  should  be enforced, then a Delivery-
                Mode other than background must be used.  If
                not  set, there is no limit to the number of
                children -- that is, the system load average
                controls this.

      MaxHeadersLength=N
                [no  short  name]  If set to a value greater
                than zero it specifies the maximum length of
                the sum of all headers.  This can be used to
                prevent a denial of service attack.  The de-
                fault is 32K.

      MaxHopCount=N
                [h]  The  maximum  hop count.  Messages that
                have been processed more than  N  times  are
                assumed  to  be  in a loop and are rejected.
                Defaults to 25.

      MaxMessageSize=N
                [no short name] Specify the maximum  message
                size  to be advertised in the ESMTP EHLO re-
                sponse.  Messages larger than this  will  be
                rejected.   If  set  to a value greater than
                zero, that value will be listed in the  SIZE
                response,  otherwise  SIZE  is advertised in
                the ESMTP EHLO response without a parameter.

      MaxMimeHeaderLength=N[/M]
                [no short name] Sets the maximum  length  of
                certain  MIME header field values to N char-
                acters.  These MIME header fields are deter-
                mined by being a member of class {checkMIME-
                TextHeaders}, which currently contains  only
                the header Content-Description.  For some of
                these headers  which  take  parameters,  the
                maximum length of each parameter is set to M
                if specified.  If /M is not  specified,  one
                half  of  N will be used.  By default, these
                values are 2048 and 1024, respectively.   To
                allow any length, a value of 0 can be speci-
                fied.

      MaxNOOPCommands=N
                Override the default of MAXNOOPCOMMANDS  for
                the  number of useless commands, see Section
                "Measures  against  Denial  of  Service  At-
                tacks".











SMM:08-118         Sendmail Installation and Operation Guide


      MaxQueueChildren=N
                [no  short  name]  When set, this limits the
                number of concurrent queue runner  processes
                to  N.   This helps to control the amount of
                system resources used  when  processing  the
                queue.  When there are multiple queue groups
                defined and the total number of  queue  run-
                ners  for  these  queue  groups would exceed
                MaxQueueChildren then the queue groups  will
                not all run concurrently. That is, some por-
                tion of the queue groups  will  run  concur-
                rently  such  that MaxQueueChildren will not
                be  exceeded,  while  the  remaining   queue
                groups will be run later (in round robin or-
                der). See also  MaxRunnersPerQueue  and  the
                section  Queue  Group  Declaration.  Notice:
                sendmail does  not  count  individual  queue
                runners, but only sets of processes that act
                on a workgroup.  Hence the actual number  of
                queue  runners  may  be lower than the limit
                imposed by MaxQueueChildren.  This  discrep-
                ancy can be large if some queue runners have
                to wait for a slow server and if  short  in-
                tervals are used.

      MaxQueueRunSize=N
                [no  short  name] The maximum number of jobs
                that will be processed  in  a  single  queue
                run.   If  not set, there is no limit on the
                size.  If you have very large  queues  or  a
                very  short queue run interval this could be
                unstable.  However, since the first  N  jobs
                in  queue  directory  order  are run (rather
                than  the  N  highest  priority  jobs)  this
                should  be  set as high as possible to avoid
                "losing" jobs that happen to  fall  late  in
                the queue directory.  Note: this option also
                restricts the number of entries  printed  by
                mailq.   That  is, if MaxQueueRunSize is set
                to a value N larger than zero, then  only  N
                entries are printed per queue group.

      MaxRecipientsPerMessage=N
                [no short name] The maximum number of recip-
                ients that will be accepted per  message  in
                an SMTP transaction.  Note: setting this too
                low can interfere  with  sending  mail  from
                MUAs  that  use SMTP for initial submission.
                If not set, there is no limit on the  number
                of recipients per envelope.

      MaxRunnersPerQueue=N
                [no   short  name]  This  sets  the  default










Sendmail Installation and Operation Guide         SMM:08-119


                maximum number of queue  runners  for  queue
                groups.   Up to N queue runners will work in
                parallel on a queue group's messages.   This
                is  useful where the processing of a message
                in the queue might delay the  processing  of
                subsequent messages. Such a delay may be the
                result of non-erroneous situations such as a
                low bandwidth connection.  May be overridden
                on a per queue group basis  by  setting  the
                Runners  option; see the section Queue Group
                Declaration.  The default is 1 when not set.

      MeToo     [m] Send to me too, even if I am in an alias
                expansion.   This  option  is deprecated and
                will be removed from a future version.

      Milter    [no short  name]  This  option  has  several
                sub(sub)options.   The  names  of the subop-
                tions are separated by dots.  At  the  first
                level the following options are available:

                    LogLevel   Log level for input mail filter actions, defaults to LogLevel.
                    macros     Specifies list of macro to transmit to filters.
                               See list below.

                The ``macros'' option has the following sub-
                options which specify the list of  macro  to
                transmit  to  milters  after a certain event
                occurred.

                    connect   After session connection start
                    helo      After EHLO/HELO command
                    envfrom   After MAIL command
                    envrcpt   After RCPT command
                    data      After DATA command.
                    eoh       After DATA command and header
                    eom       After DATA command and terminating ``.''

                By default the lists of  macros  are  empty.
                Example:

                    O Milter.LogLevel=12
                    O Milter.macros.connect=j, _, {daemon_name}


      MinFreeBlocks=N
                [b]  Insist on at least N blocks free on the
                filesystem that holds the queue files before
                accepting  email  via SMTP.  If there is in-
                sufficient space sendmail gives  a  452  re-
                sponse  to  the  MAIL command.  This invites
                the sender to try again later.











SMM:08-120         Sendmail Installation and Operation Guide


      MaxQueueAge=age
                [no short name] If this is set  to  a  value
                greater than zero, entries in the queue will
                be retried during a queue run  only  if  the
                individual retry time has been reached which
                is doubled for each  attempt.   The  maximum
                retry  time  is  limited  by  the  specified
                value.

      MinQueueAge=age
                [no short name]  Don't  process  any  queued
                jobs  that  have been in the queue less than
                the indicated time interval.   This  is  in-
                tended to allow you to get responsiveness by
                processing the queue fairly frequently with-
                out thrashing your system by trying jobs too
                often.   The  default  units  are   minutes.
                Note:  This option is ignored for queue runs
                that select a subset  of  the  queue,  i.e.,
                "-q[!][I|R|S|Q][string]"

      MustQuoteChars=s
                [no  short name] Sets the list of characters
                that must be quoted if used in a  full  name
                that  is  in  the  phrase part of a ``phrase
                <address>'' syntax.  The default is  ``'.''.
                The   characters  ``@,;:\()[]''  are  always
                added to this list.  Note: To  avoid  poten-
                tial  breakage of DKIM signatures it is use-
                ful to set

                    O MustQuoteChars=.

                Moreover, relaxed header signing  should  be
                used for DKIM signatures.

      NiceQueueRun
                [no  short  name] The priority of queue run-
                ners (nice(3)).  This value must be  greater
                or equal zero.

      NoRecipientAction
                [no  short name] The action to take when you
                receive a message that has no valid  recipi-
                ent  headers (To:, Cc:, Bcc:, or Apparently-
                To: -- the last included for  back  compati-
                bility  with old sendmails).  It can be None
                to pass the message on unmodified, which vi-
                olates  the  protocol,  Add-To  to add a To:
                header with any recipients it  can  find  in
                the envelope (which might expose Bcc: recip-
                ients), Add-Apparently-To to add  an  Appar-
                ently-To:  header  (this  is  only for back-










Sendmail Installation and Operation Guide         SMM:08-121


                compatibility and is officially deprecated),
                Add-To-Undisclosed  to  add  a  header  "To:
                undisclosed-recipients:;" to make the header
                legal  without  disclosing anything, or Add-
                Bcc to add an empty Bcc: header.

      OldStyleHeaders
                [o] Assume that the headers may  be  in  old
                format,  i.e.,  spaces  delimit names.  This
                actually turns on an adaptive algorithm:  if
                any  recipient  address  contains  a  comma,
                parenthesis, or angle bracket,  it  will  be
                assumed  that commas already exist.  If this
                flag is not on, only commas  delimit  names.
                Headers  are  always  output with commas be-
                tween the names.  Defaults to off.

      OperatorChars=charlist
                [$o macro] The list of characters  that  are
                considered to be "operators", that is, char-
                acters that delimit  tokens.   All  operator
                characters  are  tokens  by  themselves; se-
                quences of non-operator characters are  also
                tokens.  White space characters separate to-
                kens but are not tokens  themselves  --  for
                example,  "AAA.BBB"  has  three  tokens, but
                "AAA BBB" has two.  If  not  set,  Operator-
                Chars defaults to ".:@[]"; additionally, the
                characters "()<>,;"  are  always  operators.
                Note  that  OperatorChars must be set in the
                configuration file before any rulesets.

      PidFile=filename
                [no short name] Filename of  the  pid  file.
                (default  is  _PATH_SENDMAILPID).  The file-
                name is macro-expanded before it is  opened,
                and unlinked when sendmail exits.

      PostmasterCopy=postmaster
                [P] If set, copies of error messages will be
                sent to  the  named  postmaster.   Only  the
                header  of  the failed message is sent.  Er-
                rors resulting from messages with a negative
                precedence will not be sent.  Since most er-
                rors are user problems, this is probably not
                a  good  idea  on  large sites, and arguably
                contains all sorts  of  privacy  violations,
                but  it seems to be popular with certain op-
                erating systems  vendors.   The  address  is
                macro expanded at the time of delivery.  De-
                faults to no postmaster copies.












SMM:08-122         Sendmail Installation and Operation Guide


      PrivacyOptions=opt,opt,...
                [p] Set the privacy options.  ``Privacy'' is
                really  a misnomer; many of these are just a
                way of insisting on  stricter  adherence  to
                the  SMTP  protocol.  The options can be se-
                lected from:

                    public              Allow open access
                    needmailhelo        Insist on HELO or EHLO command before MAIL
                    needexpnhelo        Insist on HELO or EHLO command before EXPN
                    noexpn              Disallow EXPN entirely, implies noverb.
                    needvrfyhelo        Insist on HELO or EHLO command before VRFY
                    novrfy              Disallow VRFY entirely
                    noetrn              Disallow ETRN entirely
                    noverb              Disallow VERB entirely
                    restrictmailq       Restrict mailq command
                    restrictqrun        Restrict -q command line flag
                    restrictexpand      Restrict -bv and -v command line flags
                    noreceipts          Don't return success DSNs[20]
                    nobodyreturn        Don't return the body of a message with DSNs
                    goaway              Disallow essentially all SMTP status queries
                    authwarnings        Put X-Authentication-Warning: headers in messages
                                        and log warnings
                    noactualrecipient   Don't put X-Actual-Recipient lines in DSNs
                                        which reveal the actual account that addresses map to.

                The  "goaway" pseudo-flag sets all flags ex-
                cept  "noreceipts",  "restrictmailq",   "re-
                strictqrun", "restrictexpand", "noetrn", and
                "nobodyreturn".   If  mailq  is  restricted,
                only  people  in the same group as the queue
                directory can print  the  queue.   If  queue
                runs are restricted, only root and the owner
                of the queue directory can  run  the  queue.
                The  "restrictexpand"  pseudo-flag instructs
                sendmail to drop privileges when the -bv op-
                tion  is given by users who are neither root
                nor the TrustedUser  so  users  cannot  read
                private   aliases,  forwards,  or  :include:
                files.  It will add the "NonRootSafeAddr" to
                the  "DontBlameSendmail"  option  to prevent
                misleading unsafe address warnings.  It also
                overrides  the -v (verbose) command line op-
                tion to prevent  information  leakage.   Au-
                thentication  Warnings  add  warnings  about
                various conditions  that  may  indicate  at-
                tempts to spoof the mail system, such as us-
                ing a non-standard queue directory.
____________________
   [20]N.B.: the noreceipts flag turns off support  for  RFC
1891 (Delivery Status Notification).












Sendmail Installation and Operation Guide         SMM:08-123


      ProcessTitlePrefix=string
                [no short name]  Prefix  the  process  title
                shown  on  'ps'  listings  with string.  The
                string will be macro processed.

      QueueDirectory=dir
                [Q] The  QueueDirectory  option  serves  two
                purposes.  First, it specifies the directory
                or set of directories that comprise the  de-
                fault queue group.  Second, it specifies the
                directory D which is  the  ancestor  of  all
                queue  directories,  and which sendmail uses
                as  its  current  working  directory.   When
                sendmail  dumps  core,  it  leaves  its core
                files in D.  There are two  cases.   If  dir
                ends      with      an     asterisk     (eg,
                /var/spool/mqueue/qd*), then all of the  di-
                rectories  or  symbolic links to directories
                beginning  with  `qd'  in  /var/spool/mqueue
                will be used as queue directories of the de-
                fault  queue  group,  and  /var/spool/mqueue
                will  be  used  as  the working directory D.
                Otherwise, dir must name a  directory  (usu-
                ally  /var/spool/mqueue):  the default queue
                group consists of the single queue directory
                dir,  and  the working directory D is set to
                dir.  To define additional groups  of  queue
                directories,  use the configuration file `Q'
                command.  Do not change the queue  directory
                structure while sendmail is running.

      QueueFactor=factor
                [q]  Use factor as the multiplier in the map
                function to decide when  to  just  queue  up
                jobs  rather  than  run them.  This value is
                divided by the difference between  the  cur-
                rent load average and the load average limit
                (QueueLA option) to  determine  the  maximum
                message  priority  that  will  be sent.  De-
                faults to 600000.

      QueueLA=LA
                [x] When the system load average exceeds  LA
                and  the  QueueFactor  (q) option divided by
                the difference in the current  load  average
                and the QueueLA option plus one is less than
                the priority of the message, just queue mes-
                sages  (i.e.,  don't try to send them).  De-
                faults to 8 multiplied by the number of pro-
                cessors online on the system (if that can be
                determined).












SMM:08-124         Sendmail Installation and Operation Guide


      QueueFileMode=mode
                [no  short  name]  Default  permissions  for
                queue  files  (octal).  If not set, sendmail
                uses 0600 unless its real and effective  uid
                are different in which case it uses 0644.

      QueueSortOrder=algorithm
                [no  short name] Sets the algorithm used for
                sorting the queue.  Only the first character
                of  the  value  is  used.   Legal values are
                "host" (to order by the name  of  the  first
                host  name  of  the first recipient), "file-
                name" (to order by the  name  of  the  queue
                file  name), "time" (to order by the submis-
                sion/creation time), "random" (to order ran-
                domly), "modification" (to order by the mod-
                ification time of the qf file (older entries
                first)),  "none" (to not order), and "prior-
                ity" (to order by message  priority).   Host
                ordering  makes better use of the connection
                cache, but may tend to process low  priority
                messages  that go to a single host over high
                priority messages that go to several  hosts;
                it  probably  shouldn't be used on slow net-
                work links.  Filename and modification  time
                ordering  saves  the overhead of reading all
                of the  queued  items  before  starting  the
                queue  run.   Creation (submission) time or-
                dering is almost always a bad idea, since it
                allows  large,  bulk  mail  to go out before
                smaller, personal mail, but may have  appli-
                cability  on  some hosts with very fast con-
                nections.  Random is useful if several queue
                runners  are  started  by  hand which try to
                drain the same queue  since  odds  are  they
                will  be  working  on different parts of the
                queue at the same time.   Priority  ordering
                is the default.

      QueueTimeout=timeout
                [T]  A  synonym  for  "Timeout.queuereturn".
                Use that form instead of the  "QueueTimeout"
                form.

      RandFile  [no short name] Name of file containing ran-
                dom data or the name of the UNIX  socket  if
                EGD  is used.  A (required) prefix "egd:" or
                "file:" specifies the  type.   STARTTLS  re-
                quires this filename if the compile flag HA-
                SURANDOMDEV   is   not   set   (see    send-
                mail/README).












Sendmail Installation and Operation Guide         SMM:08-125


      ResolverOptions=options
                [I] Set resolver options.  Values can be set
                using +flag and  cleared  using  -flag;  the
                flags  can  be  "debug",  "aaonly", "usevc",
                "primary", "igntc",  "recurse",  "defnames",
                "stayopen",  "use_inet6",  or "dnsrch".  The
                string "HasWildcardMX" (without a  +  or  -)
                can   be  specified  to  turn  off  matching
                against MX records when doing name canonifi-
                cations.   The string "WorkAroundBrokenAAAA"
                (without a + or -) can be specified to  work
                around  some broken nameservers which return
                SERVFAIL (a  temporary  failure)  on  T_AAAA
                (IPv6)  lookups.  Notice: it might be neces-
                sary to apply the same (or similar)  options
                to submit.cf too.

      RequiresDirfsync
                [no  short  name] This option can be used to
                override   the   compile   time   flag   RE-
                QUIRES_DIR_FSYNC at runtime by setting it to
                false.  If the compile time flag is not set,
                the  option  is  ignored.  The flag turns on
                support for file  systems  that  require  to
                call  fsync()  for  a directory if the meta-
                data in it has been changed.  This should be
                turned  on  at  least  for older versions of
                ReiserFS;  it  is  enabled  by  default  for
                Linux.   According  to some information this
                flag is not needed anymore for kernel 2.4.16
                and newer.

      RrtImpliesDsn
                [no  short  name]  If  this option is set, a
                "Return-Receipt-To:" header causes  the  re-
                quest  of  a DSN, which is sent to the enve-
                lope sender as required by RFC 1891, not  to
                the address given in the header.

      RunAsUser=user
                [no  short name] The user parameter may be a
                user name (looked up in  /etc/passwd)  or  a
                numeric   user  id;  either  form  can  have
                ":group" attached (where group  can  be  nu-
                meric  or  symbolic).   If set to a non-zero
                (non-root) value, sendmail  will  change  to
                this  user  id  shortly  after  startup[21].
____________________
   [21]When running as a daemon, it changes to this user af-
ter accepting a connection but before reading any SMTP  com-
mands.












SMM:08-126         Sendmail Installation and Operation Guide


                This avoids  a  certain  class  of  security
                problems.   However,  this  means  that  all
                ".forward" and  ":include:"  files  must  be
                readable by the indicated user and all files
                to be written must be writable by user Also,
                all  file  and  program  deliveries  will be
                marked unsafe unless the  option  DontBlame-
                Sendmail=NonRootSafeAddr  is  set,  in which
                case the delivery will be done as user.   It
                is  also incompatible with the SafeFileEnvi-
                ronment option.  In other words, it may  not
                actually  add much to security on an average
                system, and may in fact detract  from  secu-
                rity (because other file permissions must be
                loosened).  However, it should be useful  on
                firewalls and other places where users don't
                have accounts and the aliases file  is  well
                constrained.

      RecipientFactor=fact
                [y]  The  indicated  factor  is added to the
                priority (thus lowering the priority of  the
                job)  for  each  recipient, i.e., this value
                penalizes jobs with large numbers of recipi-
                ents.  Defaults to 30000.

      RefuseLA=LA
                [X] When the system load average exceeds LA,
                refuse incoming SMTP connections.   Defaults
                to 12 multiplied by the number of processors
                online on the system (if that can be  deter-
                mined).

      RejectLogInterval=timeout
                [no  short  name] Log interval when refusing
                connections for this long (default: 3h).

      RetryFactor=fact
                [Z] The factor is added to the priority  ev-
                ery  time  a  job  is processed.  Thus, each
                time a job is processed, its  priority  will
                be  decreased  by  the  indicated value.  In
                most environments this should  be  positive,
                since  hosts that are down are all too often
                down for a long time.  Defaults to 90000.

      SafeFileEnvironment=dir
                [no short name] If this option is set, send-
                mail will do a chroot(2) call into the indi-
                cated  directory  before  doing   any   file
                writes.   If  the file name specified by the
                user begins with dir, that partial path name
                will be stripped off before writing, so (for










Sendmail Installation and Operation Guide         SMM:08-127


                example) if the SafeFileEnvironment variable
                is   set   to   "/safe"   then   aliases  of
                "/safe/logs/file" and "/logs/file"  actually
                indicate  the  same  file.  Additionally, if
                this option is set, sendmail refuses to  de-
                liver to symbolic links.

      SaveFromLine
                [f]  Save  UNIX-style  "From"  lines  at the
                front of headers.  Normally they are assumed
                redundant and discarded.

      SendMimeErrors
                [j] If set, send error messages in MIME for-
                mat (see RFC 2045 and RFC 1344 for details).
                If  disabled,  sendmail  will not return the
                DSN keyword in response to an EHLO and  will
                not do Delivery Status Notification process-
                ing as described in RFC 1891.

      ServerCertFile
                [no short name] File containing the certifi-
                cate  of  the server, i.e., this certificate
                is used when sendmail acts as  server  (used
                for STARTTLS).

      ServerKeyFile
                [no  short name] File containing the private
                key  belonging  to  the  server  certificate
                (used for STARTTLS).

      ServerSSLOptions
                A  space  or comma separated list of SSL re-
                lated options  for  the  server  side.   See
                SSL_CTX_set_options(3)   for   a  list;  the
                available values depend on the OpenSSL  ver-
                sion against which sendmail is compiled.  By
                default,  SSL_OP_ALL  -SSL_OP_TLSEXT_PADDING
                are  used  (if those options are available).
                Options can be  cleared  by  preceding  them
                with  a  minus sign.  It is also possible to
                specify numerical values, e.g., -0x0010.

      ServiceSwitchFile=filename
                [no short name] If your host operating  sys-
                tem  has a service switch abstraction (e.g.,
                /etc/nsswitch.conf     on     Solaris     or
                /etc/svc.conf  on Ultrix and DEC OSF/1) that
                service will be consulted and this option is
                ignored.   Otherwise,  this is the name of a
                file that provides the list of methods  used
                to  implement particular services.  The syn-
                tax is a series of lines, each of which is a










SMM:08-128         Sendmail Installation and Operation Guide


                sequence  of  words.   The first word is the
                service name, and following words  are  ser-
                vice types.  The services that sendmail con-
                sults directly are  "aliases"  and  "hosts."
                Service  types  can  be  "dns", "nis", "nis-
                plus", or "files" (with the caveat that  the
                appropriate  support must be compiled in be-
                fore the service  can  be  referenced).   If
                ServiceSwitchFile  is  not specified, it de-
                faults to /etc/mail/service.switch.  If that
                file does not exist, the default switch is:

                    aliases             files
                    hosts               dns nis files

                The    default   file   is   "/etc/mail/ser-
                vice.switch".

      SevenBitInput
                [7] Strip input to seven bits  for  compati-
                bility  with old systems.  This shouldn't be
                necessary.

      SharedMemoryKey
                [no short name] Key to use for shared memory
                segment;  if  not  set (or 0), shared memory
                will not be used.  If set to -1 sendmail can
                select  a  key  itself  provided  that  also
                SharedMemoryKeyFile is set.   Requires  sup-
                port  for  shared memory to be compiled into
                sendmail.  If this option is  set,  sendmail
                can  share  some  data between different in-
                stances.  For example, the number of entries
                in  a queue directory or the available space
                in a file system.  This allows for more  ef-
                ficient  program  execution,  since only one
                process needs to update the data instead  of
                each  individual  process gathering the data
                each time it is required.

      SharedMemoryKeyFile
                [no short name] If SharedMemoryKey is set to
                -1  then  the  automatically selected shared
                memory key will be stored in  the  specified
                file.

      SingleLineFromHeader
                [no  short  name]  If  set, From: lines that
                have embedded newlines  are  unwrapped  onto
                one  line.  This is to get around a botch in
                Lotus Notes that  apparently  cannot  under-
                stand legally wrapped RFC 822 headers.











Sendmail Installation and Operation Guide         SMM:08-129


      SingleThreadDelivery
                [no  short  name]  If  set, a client machine
                will never try to open two SMTP  connections
                to a single server machine at the same time,
                even in different processes.   That  is,  if
                another  sendmail is already talking to some
                host a new sendmail will  not  open  another
                connection.    This  property  is  of  mixed
                value; although this reduces the load on the
                other  machine,  it can cause mail to be de-
                layed (for example, if one sendmail  is  de-
                livering  a  huge  message,  other sendmails
                won't be able to send even small  messages).
                Also,  it  requires  another file descriptor
                (for the lock file) per connection,  so  you
                may  have  to reduce the ConnectionCacheSize
                option to avoid running out  of  per-process
                file  descriptors.  Requires the HostStatus-
                Directory option.

      SmtpGreetingMessage=message
                [$e macro] The message printed when the SMTP
                server  starts up.  Defaults to "$j Sendmail
                $v ready at $b".

      SMTPUTF8  Enable runtime support for SMTPUTF8.

      SoftBounce
                If set, issue temporary errors (4xy) instead
                of permanent errors (5xy).  This can be use-
                ful during testing of a new configuration to
                avoid erroneous bouncing of mails.

      SSLEngine Name  of  SSL  engine to use.  The available
                values depend on the OpenSSL version against
                which sendmail is compiled, see

                    openssl engine -v

                for some information.

      SSLEnginePath
                Path  to  dynamic  library  for  SSL engine.
                This option is only useful if  SSLEngine  is
                set.   If  both  are set, the engine will be
                loaded dynamically at runtime using the con-
                catenation  of  the  path,  a slash "/", the
                string "lib", the value  of  SSLEngine,  and
                the  string ".so".  If only SSLEngine is set
                then the static version  of  the  engine  is
                used.












SMM:08-130         Sendmail Installation and Operation Guide


      StatusFile=file
                [S]  Log  summary  statistics  in  the named
                file.  If no file name is  specified,  "sta-
                tistics"  is  used.   If not set, no summary
                statistics are saved.  This  file  does  not
                grow  in  size.  It can be printed using the
                mailstats(8) program.

      SuperSafe [s] This option can be set to  True,  False,
                Interactive, or PostMilter.  If set to True,
                sendmail will  be  super-safe  when  running
                things,  i.e.,  always instantiate the queue
                file, even if you are going to attempt imme-
                diate  delivery.   Sendmail always instanti-
                ates the queue file before returning control
                to the client under any circumstances.  This
                should really always be set  to  True.   The
                Interactive  value  has  been  introduced in
                8.12 and can be used together with Delivery-
                Mode=i.  It skips some synchronization calls
                which are effectively doubled  in  the  code
                execution  path  for  this  mode.  If set to
                PostMilter,  sendmail  defers  synchronizing
                the  queue  file until any milters have sig-
                naled acceptance of the message.  PostMilter
                is  useful  only when sendmail is running as
                an SMTP server; in all other  situations  it
                acts the same as True.

      TLSFallbacktoClear
                [no short name] If set, sendmail immediately
                tries an outbound connection  again  without
                STARTTLS  after  a  TLS  handshake  failure.
                Note: this applies to all  connections  even
                if  TLS  specific  requirements are set (see
                rulesets tls_rcpt and tls_client  ).   Hence
                such  requirements  will cause an error on a
                retry  without  STARTTLS.   Therefore   they
                should  only  trigger a temporary failure so
                the connection is later on tried again.

      TLSSrvOptions
                [no short name] List  of  options  for  SMTP
                STARTTLS for the server consisting of single
                characters with intervening white  space  or
                commas.  The flag ``V'' disables client ver-
                ification, and hence it is not  possible  to
                use  a client certificate for relaying.  The
                flag ``C'' removes the requirement  for  the
                TLS  server to have a cert.  This only works
                under very specific circumstances and should
                only  be used if the consequences are under-
                stood, e.g., clients may  not  work  with  a










Sendmail Installation and Operation Guide         SMM:08-131


                server using this.

      TempFileMode=mode
                [F]  The  file  mode  for  transcript files,
                files to which sendmail  delivers  directly,
                files  in  the HostStatusDirectory, and Sta-
                tusFile.  It is interpreted in octal by  de-
                fault.  Defaults to 0600.

      Timeout.type=timeout
                [r; subsumes old T option as well] Set time-
                out values.  For more information, see  sec-
                tion 4.1.

      TimeZoneSpec=tzinfo
                [t]  Set  the local time zone info to tzinfo
                -- for  example,  "PST8PDT".   Actually,  if
                this is not set, the TZ environment variable
                is cleared (so the system default is  used);
                if  set  but null, the user's TZ variable is
                used, and if set and non-null the  TZ  vari-
                able is set to this value.

      TrustedUser=user
                [no  short name] The user parameter may be a
                user name (looked up in  /etc/passwd)  or  a
                numeric user id.  Trusted user for file own-
                ership and starting  the  daemon.   If  set,
                generated  alias  databases  and the control
                socket (if configured) will automatically be
                owned by this user.

      TryNullMXList
                [w]  If  this system is the "best" (that is,
                lowest preference) MX for a given host,  its
                configuration  rules  should normally detect
                this situation and treat that condition spe-
                cially  by  forwarding  the  mail  to a UUCP
                feed, treating it  as  local,  or  whatever.
                However,  in  some  cases  (such as Internet
                firewalls) you may want to  try  to  connect
                directly to that host as though it had no MX
                records at all.  Setting this option  causes
                sendmail  to try this.  The downside is that
                errors in your configuration are  likely  to
                be  diagnosed  as "host unknown" or "message
                timed out" instead of something  more  mean-
                ingful.  This option is disrecommended.

      UnixFromLine=fromline
                [$l  macro]  Defines  the  format  used when
                sendmail must add a  UNIX-style  From_  line
                (that      is,      a     line     beginning










SMM:08-132         Sendmail Installation and Operation Guide


                "From<space>user").  Defaults  to  "From  $g
                $d".   Don't  change this unless your system
                uses a different UNIX mailbox  format  (very
                unlikely).

      UnsafeGroupWrites
                [no  short name] If set (default), :include:
                and .forward files that are  group  writable
                are  considered "unsafe", that is, they can-
                not reference programs or write directly  to
                files.   World  writable :include: and .for-
                ward files are  always  unsafe.   Note:  use
                DontBlameSendmail  instead;  this  option is
                deprecated.

      UseCompressedIPv6Addresses
                [no short name] If set, the compressed  for-
                mat  of  IPv6  addresses,  such as IPV6:::1,
                will be used, instead  of  the  uncompressed
                format, such as IPv6:0:0:0:0:0:0:0:1.

      UseErrorsTo
                [l] If there is an "Errors-To:" header, send
                error  messages  to  the  addresses   listed
                there.   They  normally  go  to the envelope
                sender.  Use of this option causes  sendmail
                to violate RFC 1123.  This option is disrec-
                ommended and deprecated.

      UserDatabaseSpec=udbspec
                [U] The user database specification.

      Verbose   [v] Run in verbose mode.  If  this  is  set,
                sendmail  adjusts options HoldExpensive (old
                c) and DeliveryMode (old d) so that all mail
                is  delivered  completely in a single job so
                that  you  can  see  the   entire   delivery
                process.  Option Verbose should never be set
                in the configuration file;  it  is  intended
                for  command  line  use only.  Note that the
                use of option Verbose can cause  authentica-
                tion information to leak, if you use a send-
                mail client to authenticate to a server.  If
                the authentication mechanism uses plain text
                passwords (as with LOGIN or PLAIN), then the
                password  could  be  compromised.   To avoid
                this, do not  install  sendmail  set-user-ID
                root, and disable the VERB SMTP command with
                a suitable PrivacyOptions setting.

      XscriptFileBufferSize=threshold
                [no short name] Set the threshold, in bytes,
                before  a memory-based queue transcript file










Sendmail Installation and Operation Guide         SMM:08-133


                becomes disk-based.   The  default  is  4096
                bytes.

      All options can be specified on the command line using
      the -O or -o flag, but most will cause sendmail to re-
      linquish  its  set-user-ID  permissions.   The options
      that will not cause this are SevenBitInput [7], Eight-
      BitMode  [8],  MinFreeBlocks  [b],  CheckpointInterval
      [C], DeliveryMode [d], ErrorMode [e], IgnoreDots  [i],
      SendMimeErrors [j], LogLevel [L], MeToo [m], OldStyle-
      Headers [o], PrivacyOptions [p], SuperSafe  [s],  Ver-
      bose [v], QueueSortOrder, MinQueueAge, DefaultCharSet,
      Dial    Delay,    NoRecipientAction,    ColonOkInAddr,
      MaxQueueRunSize,  SingleLineFromHeader,  and  AllowBo-
      gusHELO.  Actually, PrivacyOptions [p]  given  on  the
      command  line  are added to those already specified in
      the sendmail.cf  file,  i.e.,  they  can't  be  reset.
      Also, M (define macro) when defining the r or s macros
      is also considered "safe".

   5.7.  P -- Precedence Definitions

           Values for the "Precedence:" field may be defined
      using  the  P  control line.  The syntax of this field
      is:

          Pname=num

      When the name is found in a "Precedence:"  field,  the
      message  class  is  set  to  num.  Higher numbers mean
      higher precedence.  Numbers less than  zero  have  the
      special  property  that if an error occurs during pro-
      cessing the body of the message will not be  returned;
      this  is  expected  to be used for "bulk" mail such as
      through mailing  lists.   The  default  precedence  is
      zero.  For example, our list of precedences is:

          Pfirst-class=0
          Pspecial-delivery=100
          Plist=-30
          Pbulk=-60
          Pjunk=-100

      People  writing  mailing list exploders are encouraged
      to use "Precedence: list".  Older versions of sendmail
      (which discarded all error returns for negative prece-
      dences) didn't recognize this name, giving  it  a  de-
      fault  precedence of zero.  This allows list maintain-
      ers to see error returns on both old and new  versions
      of sendmail.













SMM:08-134         Sendmail Installation and Operation Guide


   5.8.  V -- Configuration Version Level

           To  provide  compatibility with old configuration
      files, the V line has been added to define  some  very
      basic  semantics of the configuration file.  These are
      not intended to be long term  supports;  rather,  they
      describe compatibility features which will probably be
      removed in future releases.

           N.B.: these version levels  have  nothing  to  do
      with the version number on the files.  For example, as
      of this writing version 10 config files (specifically,
      8.10) used version level 9 configurations.

           "Old"  configuration files are defined as version
      level one.  Version level two files make the following
      changes:

       (1)   Host  name canonification ($[ ... $]) appends a
             dot if the name is recognized; this  gives  the
             config  file  a  way of finding out if anything
             matched.  (Actually, this just initializes  the
             "host"  map with the "-a."  flag -- you can re-
             set it to anything you prefer by declaring  the
             map explicitly.)

       (2)   Default   host  name  extension  is  consistent
             throughout processing; version level  one  con-
             figurations  turned  off domain extension (that
             is, adding the local domain name)  during  cer-
             tain  points  in processing.  Version level two
             configurations are expected to include a trail-
             ing  dot  to  indicate that the name is already
             canonical.

       (3)   Local names that are  not  aliases  are  passed
             through  a new distinguished ruleset five; this
             can be used to append a local relay.  This  be-
             havior  can be prevented by resolving the local
             name with an initial `@'.  That  is,  something
             that resolves to a local mailer and a user name
             of "vikki" will be passed through ruleset five,
             but  a  user name of "@vikki" will have the `@'
             stripped, will not be  passed  through  ruleset
             five, but will otherwise be treated the same as
             the prior example.   The  expectation  is  that
             this  might be used to implement a policy where
             mail sent to "vikki" was handled by  a  central
             hub, but mail sent to "vikki@localhost" was de-
             livered directly.

           Version level three files allow # initiated  com-
      ments  on all lines.  Exceptions are backslash escaped










Sendmail Installation and Operation Guide         SMM:08-135


      # marks and the $# syntax.

           Version level four configurations are  completely
      equivalent to level three for historical reasons.

           Version level five configuration files change the
      default definition of $w to be just the  first  compo-
      nent of the hostname.

           Version level six configuration files change many
      of the local processing options (such as aliasing  and
      matching  the beginning of the address for `|' charac-
      ters) to be mailer  flags;  this  allows  fine-grained
      control  over the special local processing.  Level six
      configuration files may also use  long  option  names.
      The  ColonOkInAddr  option (to allow colons in the lo-
      cal-part of addresses) defaults on for lower  numbered
      configuration  files;  the configuration file requires
      some additional intelligence to  properly  handle  the
      RFC 822 group construct.

           Version  level seven configuration files used new
      option names to replace old macros  ($e  became  Smtp-
      GreetingMessage, $l became UnixFromLine, and $o became
      OperatorChars.  Also, prior to version seven, the  F=q
      flag  (use  250  instead  of 252 return value for SMTP
      VRFY commands) was assumed.

           Version level eight configuration files allow  $#
      on the left hand side of ruleset lines.

           Version  level  nine  configuration  files  allow
      parentheses in rulesets, i.e. they are not treated  as
      comments and hence removed.

           Version level ten configuration files allow queue
      group definitions.

           The V line may have an optional /vendor to  indi-
      cate  that  this configuration file uses modifications
      specific  to  a  particular  vendor[22].   You may use
      "/Berkeley" to emphasize that this configuration  file
      uses the Berkeley dialect of sendmail.



____________________
   [22]And of course, vendors are encouraged  to  add  them-
selves to the list of recognized vendors by editing the rou-
tine setvendor in  conf.c.   Please  send  e-mail  to  send-
mail@Sendmail.ORG to register your vendor dialect.












SMM:08-136         Sendmail Installation and Operation Guide


   5.9.  K -- Key File Declaration

           Special maps can be defined using the line:

          Kmapname mapclass arguments

      The  mapname is the handle by which this map is refer-
      enced in the rewriting rules.   The  mapclass  is  the
      name  of a type of map; these are compiled in to send-
      mail.  The arguments are interpreted depending on  the
      class;  typically,  there  would  be a single argument
      naming the file containing the map.

           Maps are referenced using the syntax:

          $( map key $@ arguments $: default $)

      where either or both of the arguments or default  por-
      tion may be omitted.  The $@ arguments may appear more
      than once.  The indicated key and arguments are passed
      to  the appropriate mapping function.  If it returns a
      value, it replaces the input.  If it does not return a
      value  and  the  default is specified, the default re-
      places the input.  Otherwise, the input is unchanged.

           The arguments are passed to the map for arbitrary
      use.  Most map classes can interpolate these arguments
      into their values using the syntax "%n" (where n is  a
      digit)  to indicate the corresponding argument.  Argu-
      ment "%0" indicates the database  key.   For  example,
      the rule

          R$- ! $+       $: $(uucp $1 $@ $2 $: $2 @ $1 . UUCP $)

      Looks  up  the UUCP name in a (user defined) UUCP map;
      if not found it turns it into ".UUCP" form.  The data-
      base might contain records like:

          decvax         %1@%0.DEC.COM
          research       %1@%0.ATT.COM

      Note that default clauses never do this mapping.

           The  built-in map with both name and class "host"
      is the host name canonicalization lookup.   Thus,  the
      syntax:

          $(host hostname$)

      is equivalent to:

          $[hostname$]











Sendmail Installation and Operation Guide         SMM:08-137


           There are many defined classes.

      cdb       Database  lookups  using the cdb(3) library.
                Sendmail must be compiled with CDB defined.

      dbm       Database lookups using the ndbm(3)  library.
                Sendmail must be compiled with NDBM defined.

      btree     Database  lookups  using the btree interface
                to the Berkeley DB library.   Sendmail  must
                be compiled with NEWDB defined.

      hash      Database lookups using the hash interface to
                the Berkeley DB library.  Sendmail  must  be
                compiled with NEWDB defined.

      nis       NIS lookups.  Sendmail must be compiled with
                NIS defined.

      nisplus   NIS+ lookups.   Sendmail  must  be  compiled
                with  NISPLUS  defined.  The argument is the
                name of the table to use  for  lookups,  and
                the  -k  and -v flags may be used to set the
                key and value columns respectively.

      hesiod    Hesiod lookups.  Sendmail must  be  compiled
                with HESIOD defined.

      ldap      LDAP  X500 directory lookups.  Sendmail must
                be compiled with LDAPMAP defined.   The  map
                supports  most of the standard arguments and
                most of the command line  arguments  of  the
                ldapsearch  program.  Note that, by default,
                if a single query matches  multiple  values,
                only the first value will be returned unless
                the -z (value separator) map option is  set.
                Also,  the -1 map flag will treat a multiple
                value return as if there were no matches.

      netinfo   NeXT NetInfo lookups.  Sendmail must be com-
                piled with NETINFO defined.

      text      Text  file  lookups.  The format of the text
                file is defined by the -k  (key  field  num-
                ber), -v (value field number), and -z (field
                delimiter) options.

      ph        PH query map.  Contributed and supported  by
                Mark Roth, roth@uiuc.edu.

      nsd       nsd map for IRIX 6.5 and later.  Contributed
                and  supported  by   Bob   Mende   of   SGI,
                mende@sgi.com.










SMM:08-138         Sendmail Installation and Operation Guide


      stab      Internal  symbol table lookups.  Used inter-
                nally for aliasing.

      implicit  Sequentially try a  list  of  available  map
                types:  hash,  dbm,  and cdb.  It is the de-
                fault for alias files if no class is  speci-
                fied.   If is no matching map type is found,
                the text version is used for the alias file,
                but other maps fail to open.

      user      Looks  up  users  using getpwnam(3).  The -v
                flag can be used to specify the name of  the
                field  to  return (although this is normally
                used only to check the existence of a user).

      host      Canonifies host domain names.  Given a  host
                name  it  calls  the name server to find the
                canonical name for that host.

      bestmx    Returns the best MX record for a  host  name
                given  as  the  key.  The current machine is
                always preferred -- that is, if the  current
                machine is one of the hosts listed as a low-
                est-preference MX record, then  it  will  be
                guaranteed to be returned.  This can be used
                to find out if this machine  is  the  target
                for  an  MX record, and mail can be accepted
                on that basis.  If the -z option  is  given,
                then all MX names are returned, separated by
                the given delimiter.  Note: the return value
                is  deterministic, i.e., even if multiple MX
                records have the same preference, they  will
                be returned in the same order.

      dns       This  map  requires the option -R to specify
                the DNS resource record type to lookup.  The
                following  types  are  supported:  A,  AAAA,
                AFSDB, CNAME, MX, NS, PTR, SRV, and TXT.   A
                map  lookup  will return only one record un-
                less the -z (value separator) option is set.
                Hence  for some types, e.g., MX records, the
                return value might be a  random  element  of
                the  results  due  to randomizing in the DNS
                resolver, if only one element is returned.

      arpa      Returns the ``reverse''  for  the  given  IP
                (IPv4 or IPv6) address, i.e., the string for
                the  PTR  lookup,   but   without   trailing
                ip6.arpa  or in-addr.arpa.  For example, the
                following configuration lines:













Sendmail Installation and Operation Guide         SMM:08-139


                    Karpa arpa
                    SArpa
                    R$+            $: $(arpa $1 $)

                work like this in test mode:

                    sendmail -bt
                    ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
                    Enter <ruleset> <address>
                    > Arpa IPv6:1:2:dead:beef:9876:0:0:1
                    Arpa               input: IPv6 : 1 : 2 : dead : beef : 9876 : 0 : 0 : 1
                    Arpa             returns: 1 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 0 . 6 . 7 . 8 . 9 . f . e . e . b . d . a . e . d . 2 . 0 . 0 . 0 . 1 . 0 . 0 . 0
                    > Arpa 1.2.3.4
                    Arpa               input: 1 . 2 . 3 . 4
                    Arpa             returns: 4 . 3 . 2 . 1


      sequence  The arguments on the `K' line are a list  of
                maps;  the  resulting map searches the argu-
                ment maps in order until it  finds  a  match
                for  the indicated key.  For example, if the
                key definition is:

                    Kmap1 ...
                    Kmap2 ...
                    Kseqmap sequence map1 map2

                then a lookup against "seqmap" first does  a
                lookup  in  map1.   If that is found, it re-
                turns immediately.  Otherwise, the same  key
                is used for map2.

      syslog    the  key  is  logged  via  syslogd(8).   The
                lookup returns the empty string.

      switch    Much like the "sequence" map except that the
                order  of  maps is determined by the service
                switch.  The argument is  the  name  of  the
                service to be looked up; the values from the
                service switch are appended to the map  name
                to  create new map names.  For example, con-
                sider the key definition:

                    Kali switch aliases

                together with the service switch entry:

                    aliases        nis files

                This causes a query against the map "ali" to
                search  maps named "ali.nis" and "ali.files"
                in that order.











SMM:08-140         Sendmail Installation and Operation Guide


      dequote   Strip double quotes (")  from  a  name.   It
                does  not  strip  backslashes,  and will not
                strip quotes if the resulting  string  would
                contain  unscannable  syntax (that is, basic
                errors like unbalanced angle brackets;  more
                sophisticated  errors  such as unknown hosts
                are not checked).  The  intent  is  for  use
                when trying to accept mail from systems such
                as DECnet that routinely  quote  odd  syntax
                such as

                    "49ers::ubell"

                A typical usage is probably something like:

                    Kdequote dequote

                    ...

                    R$-            $: $(dequote $1 $)
                    R$- $+         $: $>3 $1 $2

                Care must be taken to prevent unexpected re-
                sults; for example,

                    "|someprogram < input > output"

                will have quotes stripped, but the result is
                probably  not  what you had in mind.  Fortu-
                nately these cases are rare.

      regex     The map definition on the K line contains  a
                regular  expression.   Any key input is com-
                pared to that  expression  using  the  POSIX
                regular   expressions   routines  regcomp(),
                regerr(), and regexec().  Refer to the docu-
                mentation for those routines for more infor-
                mation about the regular  expression  match-
                ing.  No rewriting of the key is done if the
                -m flag is used.  Without  it,  the  key  is
                discarded  or  if  -s if used, it is substi-
                tuted by the substring matches, delimited by
                $|  or  the string specified with the -d op-
                tion.  The options available for the map are

                    -n  not
                    -f  case sensitive
                    -b  basic regular expressions (default is extended)
                    -s  substring match
                    -d  set the delimiter string used for -s
                    -a  append string to key
                    -m  match only, do not replace/discard value
                    -D  perform no lookup in deferred delivery mode.










Sendmail Installation and Operation Guide         SMM:08-141


                The -s option can include an optional param-
                eter  which  can  be used to select the sub-
                strings in the result of  the  lookup.   For
                example,

                    -s1,3,4

                The  delimiter  string  specified via the -d
                option is the sequence of characters after d
                ending  at  the first space.  Hence it isn't
                possible to specify a space as delimiter, so
                if  the  option is immediately followed by a
                space the delimiter string is  empty,  which
                means the substrings are joined.

                Notes: to match a $ in a string, \$$ must be
                used.  If the pattern contains spaces,  they
                must be replaced with the blank substitution
                character, unless it is space itself.

      program   The arguments on the K line are the pathname
                to  a  program and any initial parameters to
                be passed.  When the map is called, the  key
                is  added  to the initial parameters and the
                program is invoked as the default user/group
                id.   The  first  line of standard output is
                returned as the value of the  lookup.   This
                has  many  potential  security problems, and
                has terrible performance; it should be  used
                only when absolutely necessary.

      macro     Set or clear a macro value.  To set a macro,
                pass the value as the first argument in  the
                map  lookup.   To clear a macro, do not pass
                an argument in the map lookup.  The map  al-
                ways  returns  the empty string.  Example of
                typical usage include:

                    Kstorage macro

                    ...

                    # set macro ${MyMacro} to the ruleset match
                    R$+ $: $(storage {MyMacro} $@ $1 $) $1
                    # set macro ${MyMacro} to an empty string
                    R$* $: $(storage {MyMacro} $@ $) $1
                    # clear macro ${MyMacro}
                    R$- $: $(storage {MyMacro} $) $1


      arith     Perform simple arithmetic  operations.   The
                operation  is  given as key, currently +, -,
                *, /, %, |, & (bitwise OR, AND), l (for less










SMM:08-142         Sendmail Installation and Operation Guide


                than),  =, and r (for random) are supported.
                The two operands  are  given  as  arguments.
                The  lookup returns the result of the compu-
                tation, i.e., TRUE or FALSE for comparisons,
                integer  values  otherwise.   The r operator
                returns a pseudo-random number  whose  value
                lies  between  the  first and second operand
                (which requires that the  first  operand  is
                smaller than the second).  All options which
                are possible for maps are ignored.  A simple
                example is:

                    Kcomp arith

                    ...

                    Scheck_etrn
                    R$* $: $(comp l $@ $&{load_avg} $@ 7 $) $1
                    RFALSE$# error ...


      socket    The  socket  map uses a simple request/reply
                protocol over TCP or UNIX domain sockets  to
                query an external server.  Both requests and
                replies are text based and encoded  as  net-
                strings,  i.e.,  a  string "hello there" be-
                comes:

                    11:hello there,

                Note: neither requests nor replies end  with
                CRLF.

                The  request  consists  of  the database map
                name and the lookup key separated by a space
                character:


                    <mapname> ' ' <key>


                The  server responds with a status indicator
                and the result (if any):


                    <status> ' ' <result>


                The status indicator specifies the result of
                the  lookup  operation  itself and is one of
                the following upper case words:












Sendmail Installation and Operation Guide         SMM:08-143


                    OK       the key was found, result contains the looked up value
                    NOTFOUND the key was not found, the result is empty
                    TEMP     a temporary failure occurred
                    TIMEOUT  a timeout occurred on the server side
                    PERM     a permanent failure occurred


                In case of errors (status TEMP,  TIMEOUT  or
                PERM)  the  result  field may contain an ex-
                planatory message.  However, the explanatory
                message is not used any further by sendmail.

                Example replies:

                    31:OK resolved.address@example.com,



                    56:OK error:550 5.7.1 User does not accept mail from sender,


                in case of successful lookups, or:

                    8:NOTFOUND,


                in case the key was not found, or:

                    55:TEMP this text explains that we had a temporary failure,


                in case of a temporary map lookup failure.

                The  socket map uses the same syntax as mil-
                ters (see Section "X -- Mail Filter (Milter)
                Definitions")  to  specify  the  remote end-
                point, e.g.,

                    Ksocket mySocketMap inet:12345@127.0.0.1


                If multiple socket maps define the same  re-
                mote endpoint, they will share a single con-
                nection to this endpoint.

           Most of these accept as arguments  the  same  op-
      tional flags and a filename (or a mapname for NIS; the
      filename is the root of the  database  path,  so  that
      ".db"  or  some  other  extension  appropriate for the
      database type will be added to get the actual database
      name).  Known flags are:












SMM:08-144         Sendmail Installation and Operation Guide


      -o        Indicates  that this map is optional -- that
                is, if it cannot be opened, no error is pro-
                duced,  and  sendmail  will behave as if the
                map existed but was empty.

      -N, -O    If neither -N or -O are specified,  sendmail
                uses an adaptive algorithm to decide whether
                or not to look for null bytes on the end  of
                keys.  It starts by trying both; if it finds
                any key with a  null  byte  it  never  tries
                again  without  a  null byte and vice versa.
                If -N is specified it never tries without  a
                null  byte  and  if -O is specified it never
                tries with a  null  byte.   Setting  one  of
                these can speed matches but are never neces-
                sary.  If both  -N  and  -O  are  specified,
                sendmail  will  never try any matches at all
                -- that is, everything will appear to fail.

      -ax       Append the string x on  successful  matches.
                For  example, the default host map appends a
                dot on successful matches.

      -Tx       Append the string x on  temporary  failures.
                For  example,  x  would be appended if a DNS
                lookup returned "server failed"  or  an  NIS
                lookup  could not locate a server.  See also
                the -t flag.

      -f        Do not fold upper to lower case before look-
                ing up the key.

      -m        Match  only  (without  replacing the value).
                If you only care about the  existence  of  a
                key  and  not  the  value (as you might when
                searching the NIS map "hosts.byname" for ex-
                ample), this flag prevents the map from sub-
                stituting the value.  However, The -a  argu-
                ment  is  still appended on a match, and the
                default is still taken if the match fails.

      -kkeycol  The key column name  (for  NIS+)  or  number
                (for  text  lookups).  For LDAP maps this is
                an LDAP filter string in  which  %s  is  re-
                placed  with  the  literal  contents  of the
                lookup key and %0 is replaced with the  LDAP
                escaped contents of the lookup key according
                to RFC 2254.  If the flag -K is  used,  then
                %1 through %9 are replaced with the LDAP es-
                caped contents of the arguments specified in
                the map lookup.












Sendmail Installation and Operation Guide         SMM:08-145


      -vvalcol  The  value  column name (for NIS+) or number
                (for text lookups).  For LDAP maps  this  is
                the name of one or more attributes to be re-
                turned; multiple attributes can be separated
                by commas.  If not specified, all attributes
                found in the match will  be  returned.   The
                attributes  listed  can  also include a type
                and  one  or  more  objectClass  values  for
                matching as described in the LDAP section.

      -zdelim   The column delimiter (for text lookups).  It
                can be a single character or one of the spe-
                cial  strings  "\n" or "\t" to indicate new-
                line or tab respectively.   If  omitted  en-
                tirely, the column separator is any sequence
                of white space.  For  LDAP  and  some  other
                maps this is the separator character to com-
                bine multiple values into  a  single  return
                string.   If  not  set, the LDAP lookup will
                only return the first match found.  For  DNS
                maps  this  is  the  separator  character at
                which the result of a query is cut off if is
                too long.

      -t        Normally, when a map attempts to do a lookup
                and  the  server   fails   (e.g.,   sendmail
                couldn't  contact  any  name server; this is
                not the same as an entry not being found  in
                the  map),  the  message  being processed is
                queued for future processing.  The  -t  flag
                turns  off this behavior, letting the tempo-
                rary failure (server down) act as though  it
                were  a permanent failure (entry not found).
                It is particularly useful for  DNS  lookups,
                where   someone  else's  misconfigured  name
                server can cause problems on  your  machine.
                However,  care  must be taken to ensure that
                you don't bounce mail that would be resolved
                correctly  if  you  tried  again.   A common
                strategy is to forward such mail to another,
                possibly better connected, mail server.

      -D        Perform no lookup in deferred delivery mode.
                This flag is set by  default  for  the  host
                map.

      -Sspacesub
                The  character to use to replace space char-
                acters after a successful map  lookup  (esp.
                useful for regex and syslog maps).

      -sspacesub
                For  the  dequote map only, the character to










SMM:08-146         Sendmail Installation and Operation Guide


                use to replace space characters after a suc-
                cessful dequote.

      -q        Don't dequote the key before lookup.

      -Llevel   For  the  syslog  map only, it specifies the
                level to use for the syslog call.

      -A        When rebuilding an alias file, the  -A  flag
                causes duplicate entries in the text version
                to be merged.  For example, two entries:

                    list:    user1, user2
                    list:    user3

                would be treated as though it were the  sin-
                gle entry

                    list:    user1, user2, user3

                in the presence of the -A flag.

           Some  additional flags are available for the host
      and dns maps:

      -d        delay: specify the resolver's retransmission
                time interval (in seconds).

      -r        retry:  specify  the  number of times to re-
                transmit a resolver query.

           The dns map has another flag:

      -B        basedomain: specify a domain that is  always
                appended to queries.

           Socket maps have an optional flag:

      -d        timeout:  specify  the  timeout (in seconds)
                for  communication  with  the   socket   map
                server.

           The following additional flags are present in the
      ldap map only:

      -ctimeout Set the LDAP network timeout.  sendmail must
                be  compiled with -DLDAP_OPT_NETWORK_TIMEOUT
                to use this flag.

      -R        Do not auto chase referrals.  sendmail  must
                be  compiled  with  -DLDAP_REFERRALS  to use
                this flag.











Sendmail Installation and Operation Guide         SMM:08-147


      -n        Retrieve attribute names only.

      -Vsep     Retrieve both attributes name and  value(s),
                separated by sep.

      -rderef   Set  the  alias dereference option to one of
                never, always, search, or find.

      -sscope   Set search scope to one of  base,  one  (one
                level), or sub (subtree).

      -hhost    LDAP  server  hostname.  Some LDAP libraries
                allow you to specify  multiple,  space-sepa-
                rated  hosts  for  redundancy.  In addition,
                each of the hosts listed can be followed  by
                a  colon  and  a port number to override the
                default LDAP port.

      -pport    LDAP service port.

      -H LDAPURI
                Use the specified LDAP URI instead of speci-
                fying  the hostname and port separately with
                the -h and -p options shown above.  For  ex-
                ample,

                    -h server.example.com -p 389 -b dc=example,dc=com

                is equivalent to

                    -H ldap://server.example.com:389 -b dc=example,dc=com

                If  the  LDAP  library supports it, the LDAP
                URI format however  can  also  request  LDAP
                over   SSL  by  using  ldaps://  instead  of
                ldap://.  For example:

                    O LDAPDefaultSpec=-H ldaps://ldap.example.com -b dc=example,dc=com

                Similarly, if the LDAP library supports  it,
                It can also be used to specify a UNIX domain
                socket using ldapi://:

                    O LDAPDefaultSpec=-H ldapi://socketfile -b dc=example,dc=com


      -bbase    LDAP search base.

      -ltimelimit
                Time limit for LDAP queries.

      -Zsizelimit
                Size (number of matches) limit for  LDAP  or










SMM:08-148         Sendmail Installation and Operation Guide


                DNS queries.

      -ddistinguished_name
                The  distinguished  name  to use to login to
                the LDAP server.

      -Mmethod  The  method  to  authenticate  to  the  LDAP
                server.   Should  be  one of LDAP_AUTH_NONE,
                LDAP_AUTH_SIMPLE, or  LDAP_AUTH_KRBV4.   The
                leading  LDAP_AUTH_  can  be omitted and the
                value is case-insensitive.

      -Ppasswordfile
                The file containing the secret key  for  the
                LDAP_AUTH_SIMPLE  authentication  method  or
                the name of the  Kerberos  ticket  file  for
                LDAP_AUTH_KRBV4.

      -1        Force  LDAP  searches  to  only succeed if a
                single match is found.  If  multiple  values
                are  found,  the  search is treated as if no
                match was found.

      -wversion Set the LDAP API/protocol  version  to  use.
                The  default  depends on the LDAP client li-
                braries in use.   For  example,  -w  3  will
                cause  sendmail  to use LDAPv3 when communi-
                cating with the LDAP server.

      -K        Treat the LDAP search key as  multi-argument
                and  replace  %1  through %9 in the key with
                the LDAP escaped contents of the lookup  ar-
                guments specified in the map lookup.

           The dbm map appends the strings ".pag" and ".dir"
      to the given filename; the hash and btree maps  append
      ".db".  For example, the map specification

          Kuucp dbm -o -N /etc/mail/uucpmap

      specifies an optional map named "uucp" of class "dbm";
      it always has null bytes at the end of  every  string,
      and       the       data       is      located      in
      /etc/mail/uucpmap.{dir,pag}.

           The program makemap(8) can be used to build data-
      base-oriented  maps.   It takes at least the following
      flags (for a complete list see its man page):

      -f        Do not fold upper to lower case in the map.

      -N        Include null bytes in keys.











Sendmail Installation and Operation Guide         SMM:08-149


      -o        Append to an existing (old) file.

      -r        Allow replacement  of  existing  keys;  nor-
                mally,  re-inserting  an  existing key is an
                error.

      -v        Print what is happening.

      The sendmail daemon does not have to be  restarted  to
      read the new maps as long as you change them in place;
      file locking is used so that the maps  won't  be  read
      while they are being updated.

           New classes can be added in the routine setupmaps
      in file conf.c.

   5.10.  Q -- Queue Group Declaration

           In addition to the option  QueueDirectory,  queue
      groups  can be declared that define a (group of) queue
      directories under a common name.   The  syntax  is  as
      follows:

          Qname {, field=value}+

      where name is the symbolic name of the queue group un-
      der which it can be referenced in various  places  and
      the "field=value" pairs define attributes of the queue
      group.  The name must  only  consist  of  alphanumeric
      characters.  Fields are:

      Flags     Flags for this queue group.

      Nice      The  nice(2)  increment for the queue group.
                This value must be greater or equal zero.

      Interval  The time between two queue runs.

      Path      The queue directory of the group (required).

      Runners   The number of  parallel  runners  processing
                the  queue.   Note  that  F=f must be set if
                this value is greater than one.

      Jobs      The maximum number of jobs (messages  deliv-
                ered) per queue run.

      recipients
                The  maximum  number of recipients per enve-
                lope.  Envelopes with more than this  number
                of  recipients  will  be split into multiple
                envelopes in the same queue directory.   The
                default value 0 means no limit.










SMM:08-150         Sendmail Installation and Operation Guide


      Only the first character of the field name is checked.

           By default, a queue group named mqueue is defined
      that uses the value of the  QueueDirectory  option  as
      path.   Notice:  all  paths  that  are  used for queue
      groups  must  be  subdirectories  of   QueueDirectory.
      Since  they  can  be symbolic links, this isn't a real
      restriction, If QueueDirectory uses a  wildcard,  then
      the  directory one level up is considered the ``base''
      directory  which  all  other  queue  directories  must
      share.  Please make sure that the queue directories do
      not overlap, e.g., do not specify

          O QueueDirectory=/var/spool/mqueue/*
          Qone, P=/var/spool/mqueue/dir1
          Qtwo, P=/var/spool/mqueue/dir2

      because this also includes "dir1" and  "dir2"  in  the
      default queue group.  However,

          O QueueDirectory=/var/spool/mqueue/main*
          Qone, P=/var/spool/mqueue/dir
          Qtwo, P=/var/spool/mqueue/other*

      is a valid queue group specification.

           Options listed in the ``Flags'' field can be used
      to modify the behavior of a queue  group.   The  ``f''
      flag  must  be  set if multiple queue runners are sup-
      posed to work on the entries in a queue group.  Other-
      wise  sendmail  will  work on the entries strictly se-
      quentially.

           The ``Interval''  field  sets  the  time  between
      queue  runs.   If  no queue group specific interval is
      set, then the parameter of the -q option from the com-
      mand line is used.

           To control the overall number of concurrently ac-
      tive queue runners the option MaxQueueChildren can  be
      set.   This  limits  the  number of processes used for
      running the queues to MaxQueueChildren, though at  any
      one  time fewer processes may be active as a result of
      queue options, completed queue runs, system load, etc.

           The maximum number of queue runners for an  indi-
      vidual  queue  group can be controlled via the Runners
      option.  If set to 0, entries in the queue will not be
      processed,  which  is  useful  to ``quarantine'' queue
      files.  The number of runners per queue group may also
      be  set  with the option MaxRunnersPerQueue, which ap-
      plies to queue groups that have no  individual  limit.
      That   is,   the   default   value   for   Runners  is










Sendmail Installation and Operation Guide         SMM:08-151


      MaxRunnersPerQueue if set, otherwise 1.

           The field Jobs describes the  maximum  number  of
      jobs  (messages delivered) per queue run, which is the
      queue group specific value of MaxQueueRunSize.

           Notice: queue groups should be declared after all
      queue  related  options  have  been  set because queue
      groups take their defaults from those options.  If  an
      option  is  set  after  a queue group declaration, the
      values of options in the queue group are  set  to  the
      defaults of sendmail unless explicitly set in the dec-
      laration.

           Each envelope is assigned to a queue group  based
      on  the  algorithm described in section ``Queue Groups
      and Queue Directories''.

   5.11.  X -- Mail Filter (Milter) Definitions

           The sendmail Mail Filter API (Milter) is designed
      to  allow third-party programs access to mail messages
      as they are being processed in order to  filter  meta-
      information  and  content.   They  are declared in the
      configuration file as:

          Xname {, field=value}*

      where name is the name of the filter (used  internally
      only)  and the "field=name" pairs define attributes of
      the filter.  Also see the documentation for the Input-
      MailFilters option for more information.

           Fields are:

          Socket    The socket specification
          Flags     Special flags for this filter
          Timeouts  Timeouts for this filter

      Only  the first character of the field name is checked
      (it's case-sensitive).

           The socket specification is one of the  following
      forms:

          S=inet: port @ host


          S=inet6: port @ host


          S=local: path











SMM:08-152         Sendmail Installation and Operation Guide


      The  first two describe an IPv4 or IPv6 socket listen-
      ing on a certain port at a given host or  IP  address.
      The  final  form  describes  a  named  socket  on  the
      filesystem at the given path.

           The following flags may be set in the filter  de-
      scription.

      R   Reject connection if filter unavailable.

      T   Temporary fail connection if filter unavailable.

           If  neither F=R nor F=T is specified, the message
      is passed through sendmail in case of filter errors as
      if the failing filters were not present.

           The timeouts can be set using the four fields in-
      side of the T= equate:

      C   Timeout for connecting to a filter.  If set to  0,
          the system's connect() timeout will be used.

      S   Timeout  for sending information from the MTA to a
          filter.

      R   Timeout for reading reply from the filter.

      E   Overall timeout between sending end-of-message  to
          filter and waiting for the final acknowledgment.

           Note  the separator between each timeout field is
      a  ';'.   The  default  values  (if  not   set)   are:
      T=C:5m;S:10s;R:10s;E:5m  where  s  is seconds and m is
      minutes.

           Examples:

          Xfilter1, S=local:/var/run/f1.sock, F=R
          Xfilter2, S=inet6:999@localhost, F=T, T=S:1s;R:1s;E:5m
          Xfilter3, S=inet:3333@localhost, T=C:2m


   5.12.  The User Database

           The user  database  is  deprecated  in  favor  of
      ``virtusertable''  and  ``genericstable'' as explained
      in the file cf/README.  If you have a version of send-
      mail  with  the user database package compiled in, the
      handling of sender and recipient  addresses  is  modi-
      fied.

           The  location of this database is controlled with
      the UserDatabaseSpec option.










Sendmail Installation and Operation Guide         SMM:08-153


      5.12.1.  Structure of the user database

              The database is a sorted (BTree-based)  struc-
         ture.  User records are stored with the key:

             user-name:field-name

         The   sorted  database  format  ensures  that  user
         records are clustered  together.   Meta-information
         is always stored with a leading colon.

              Field  names define both the syntax and seman-
         tics of the value.  Defined fields include:

         maildrop  The  delivery  address  for  this   user.
                   There  may  be  multiple  values  of this
                   record.   In  particular,  mailing  lists
                   will  have  one  maildrop record for each
                   user on the list.

         mailname  The outgoing mailname for this user.  For
                   each  outgoing  name,  there should be an
                   appropriate maildrop record for that name
                   to  allow  return  mail.   See  also :de-
                   fault:mailname.

         mailsender
                   Changes any mail sent to this address  to
                   have the indicated envelope sender.  This
                   is intended for mailing lists,  and  will
                   normally  be  the  name of an appropriate
                   -request address.  It is very similar  to
                   the owner-list syntax in the alias file.

         fullname  The full name of the user.

         office-address
                   The office address for this user.

         office-phone
                   The office phone number for this user.

         office-fax
                   The office FAX number for this user.

         home-address
                   The home address for this user.

         home-phone
                   The home phone number for this user.

         home-fax  The home FAX number for this user.











SMM:08-154         Sendmail Installation and Operation Guide


         project   A (short) description of the project this
                   person is affiliated with.  In  the  Uni-
                   versity  this  is  often just the name of
                   their graduate advisor.

         plan      A pointer to a file from which  plan  in-
                   formation can be gathered.

              As of this writing, only a few of these fields
         are actually being used by sendmail:  maildrop  and
         mailname.   A  finger  program  that uses the other
         fields is planned.

      5.12.2.  User database semantics

              When the rewriting rules submit an address  to
         the  local  mailer, the user name is passed through
         the alias file.  If no alias is found  (or  if  the
         alias  points  back  to the same address), the name
         (with ":maildrop" appended) is then used as  a  key
         in  the  user  database.  If no match occurs (or if
         the maildrop points at the same address),  forward-
         ing is tried.

              If  the  first token of the user name returned
         by ruleset 0 is an  "@"  sign,  the  user  database
         lookup  is  skipped.   The  intent is that the user
         database will act as a set of defaults for a  clus-
         ter  (in  our case, the Computer Science Division);
         mail sent to a specific machine should ignore these
         defaults.

              When  mail  is  sent,  the name of the sending
         user is looked up in the database.   If  that  user
         has  a  "mailname" record, the value of that record
         is used as their outgoing  name.   For  example,  I
         might have a record:

             eric:mailnameEric.Allman@CS.Berkeley.EDU

         This  would  cause  my  outgoing mail to be sent as
         Eric.Allman.

              If a "maildrop" is found for the user, but  no
         corresponding  "mailname" record exists, the record
         ":default:mailname" is consulted.  If present, this
         is  the  name of a host to override the local host.
         For example,  in  our  case  we  would  set  it  to
         "CS.Berkeley.EDU".  The effect is that anyone known
         in the database gets their outgoing mail stamped as
         "user@CS.Berkeley.EDU",  but  people  not listed in
         the database use the local hostname.











Sendmail Installation and Operation Guide         SMM:08-155


      5.12.3.  Creating the database[23]

              The  user  database  is built from a text file
         using the makemap utility (in the  distribution  in
         the  makemap subdirectory).  The text file is a se-
         ries of lines corresponding to userdb records; each
         line  has  a  key  and  a  value separated by white
         space.  The key is always in the  format  described
         above -- for example:

             eric:maildrop

         This  file is normally installed in a system direc-
         tory;   for   example,   it   might    be    called
         /etc/mail/userdb.   To make the database version of
         the map, run the program:

             makemap btree /etc/mail/userdb < /etc/mail/userdb

         Then create a config file that uses this.  For  ex-
         ample,  using  the V8 M4 configuration, include the
         following line in your .mc file:

             define(`confUSERDB_SPEC', /etc/mail/userdb)


6.  OTHER CONFIGURATION

        There are some configuration  changes  that  can  be
   made  by  recompiling  sendmail.   This section describes
   what changes can be made and what has to be  modified  to
   make  them.  In most cases this should be unnecessary un-
   less you are porting sendmail to a new environment.

   6.1.  Parameters in devtools/OS/$oscf

           These parameters are  intended  to  describe  the
      compilation  environment,  not site policy, and should
      normally be defined in the operating system configura-
      tion file.  This section needs a complete rewrite.

      NDBM      If  set,  the new version of the DBM library
                that allows multiple databases will be used.
                If  neither  CDB, NDBM, nor NEWDB are set, a
                much less efficient method of  alias  lookup
                is used.
____________________
   [23]These instructions are known to be incomplete.  Other
features  are available which provide similar functionality,
e.g., virtual hosting and mapping  local  addresses  into  a
generic form as explained in cf/README.












SMM:08-156         Sendmail Installation and Operation Guide


      CWDB      If set, use the cdb (tinycdb) package.

      NEWDB     If  set,  use  the new database package from
                Berkeley (from  4.4BSD).   This  package  is
                substantially  faster  than DBM or NDBM.  If
                NEWDB and NDBM are both set,  sendmail  will
                read  DBM  files,  but  will  create and use
                NEWDB files.

      NIS       Include support for NIS.   If  set  together
                with both NEWDB and NDBM, sendmail will cre-
                ate both DBM and NEWDB files if and only  if
                an  alias file includes the substring "/yp/"
                in the name.  This is intended for  compati-
                bility  with  Sun Microsystems' mkalias pro-
                gram used on YP masters.

      NISPLUS   Compile in support for NIS+.

      NETINFO   Compile in support for  NetInfo  (NeXT  sta-
                tions).

      LDAPMAP   Compile  in  support  for LDAP X500 queries.
                Requires libldap and liblber from the  Umich
                LDAP  3.2  or  3.3 release or equivalent li-
                braries for other  LDAP  libraries  such  as
                OpenLDAP.

      HESIOD    Compile in support for Hesiod.

      MAP_NSD   Compile in support for IRIX NSD lookups.

      MAP_REGEX Compile  in  support  for regular expression
                matching.

      DNSMAP    Compile in support for DNS  map  lookups  in
                the sendmail.cf file.

      PH_MAP    Compile in support for ph lookups.

      SASL      Compile in support for SASL, a required com-
                ponent for SMTP Authentication support.

      STARTTLS  Compile in support for STARTTLS.

      EGD       Compile in support for the "Entropy  Gather-
                ing  Daemon"  to  provide better random data
                for TLS.

      TCPWRAPPERS
                Compile in support for TCP Wrappers.












Sendmail Installation and Operation Guide         SMM:08-157


      _PATH_SENDMAILCF
                The pathname of the sendmail.cf file.

      _PATH_SENDMAILPID
                The pathname of the sendmail.pid file.

      SM_CONF_SHM
                Compile in support for  shared  memory,  see
                section about "/var/spool/mqueue".

      MILTER    Compile  in  support for contacting external
                mail filters built with the Milter API.

           There are also several compilation flags to indi-
      cate the environment such as "_AIX3" and "_SCO_unix_".
      See the sendmail/README file for the latest  scoop  on
      these flags.

      6.1.1.  For Future Releases

              sendmail  often  contains compile time options
         For Future Releases (prefix _FFR_) which  might  be
         enabled  in a subsequent version or might simply be
         removed as they turned out not to be really useful.
         These  features  are  usually not documented but if
         they are, then the required (FFR) compile time  op-
         tions  are listed here for rulesets and macros, and
         in cf/README for mc/cf options.  FFR compile  times
         options must be enabled when the sendmail binary is
         built from source.  Enabled FFRs in a binary can be
         listed with

             sendmail -d0.13 < /dev/null | grep FFR


   6.2.  Parameters in sendmail/conf.h

           Parameters and compilation options are defined in
      conf.h.  Most of these need not normally  be  tweaked;
      common  parameters  are  all in sendmail.cf.  However,
      the sizes of certain primitive vectors, etc., are  in-
      cluded in this file.  The numbers following the param-
      eters are their default value.

           This document is not the best source of  informa-
      tion  for  compilation  flags  in  conf.h -- see send-
      mail/README or sendmail/conf.h itself.

      MAXLINE [2048]
                  The maximum line length of any input line.
                  If  message  lines exceed this length they
                  will still be  processed  correctly;  how-
                  ever,  header  lines,  configuration  file










SMM:08-158         Sendmail Installation and Operation Guide


                  lines, alias lines, etc., must fit  within
                  this limit.

      MAXNAME [256]
                  The  maximum length of any name, such as a
                  host or a user name.

      MAXPV [256] The maximum number of  parameters  to  any
                  mailer.  This limits the number of recipi-
                  ents that may be passed  in  one  transac-
                  tion.  It can be set to any arbitrary num-
                  ber above about 10,  since  sendmail  will
                  break  up  a delivery into smaller batches
                  as needed.  A  higher  number  may  reduce
                  load on your system, however.

      MAXQUEUEGROUPS [50]
                  The maximum number of queue groups.

      MAXATOM [1000]
                  The  maximum number of atoms (tokens) in a
                  single address.  For example, the  address
                  "eric@CS.Berkeley.EDU" is seven atoms.

      MAXMAILERS [25]
                  The  maximum number of mailers that may be
                  defined in the configuration  file.   This
                  value is defined in include/sendmail/send-
                  mail.h.

      MAXRWSETS [200]
                  The maximum number of rewriting sets  that
                  may  be  defined.  The first half of these
                  are  reserved  for  numeric  specification
                  (e.g.,  ``S92''), while the upper half are
                  reserved   for    auto-numbering    (e.g.,
                  ``Sfoo'').   Thus,  with a value of 200 an
                  attempt to use ``S99'' will  succeed,  but
                  ``S100'' will fail.

      MAXPRIORITIES [25]
                  The  maximum  number  of  values  for  the
                  "Precedence:" field that  may  be  defined
                  (using the P line in sendmail.cf).

      MAXUSERENVIRON [100]
                  The  maximum  number  of items in the user
                  environment that will be passed to  subor-
                  dinate mailers.

      MAXMXHOSTS [100]
                  The  maximum  number of MX records we will
                  accept for any single host.










Sendmail Installation and Operation Guide         SMM:08-159


      MAXMAPSTACK [12]
                  The maximum number of  maps  that  may  be
                  "stacked" in a sequence class map.

      MAXMIMEARGS [20]
                  The  maximum number of arguments in a MIME
                  Content-Type: header; additional arguments
                  will be ignored.

      MAXMIMENESTING [20]
                  The  maximum  depth to which MIME messages
                  may be nested (that is, nested Message  or
                  Multipart  documents;  this does not limit
                  the number of components in a single  Mul-
                  tipart document).

      MAXDAEMONS [10]
                  The  maximum  number  of  sockets sendmail
                  will open  for  accepting  connections  on
                  different ports.

      MAXMACNAMELEN [25]
                  The maximum length of a macro name.

      A  number  of  other compilation options exist.  These
      specify whether or not specific code  should  be  com-
      piled in.  Ones marked with * are 0/1 valued.

      NETINET*    If set, support for Internet protocol net-
                  working is compiled in.  Previous versions
                  of  sendmail  referred  to this as DAEMON;
                  this old usage is now incorrect.  Defaults
                  on;  turn  it  off in the Makefile if your
                  system doesn't support the Internet proto-
                  cols.

      NETINET6*   If  set,  support  for  IPv6 networking is
                  compiled in.  It must  be  separately  en-
                  abled  by  adding  DaemonPortOptions  set-
                  tings.

      NETISO*     If set, support for ISO protocol  network-
                  ing  is compiled in (it may be appropriate
                  to #define this in the Makefile instead of
                  conf.h).

      NETUNIX*    If set, support for UNIX domain sockets is
                  compiled in.  This  is  used  for  control
                  socket support.

      LOG         If  set, the syslog routine in use at some
                  sites is used.   This  makes  an  informa-
                  tional   log   record   for  each  message










SMM:08-160         Sendmail Installation and Operation Guide


                  processed, and makes a higher priority log
                  record   for   internal   system   errors.
                  STRONGLY RECOMMENDED --  if  you  want  no
                  logging,  turn it off in the configuration
                  file.

      MATCHGECOS* Compile in the code to do  ``fuzzy  match-
                  ing''  on  the GECOS field in /etc/passwd.
                  This also requires that the MatchGECOS op-
                  tion be turned on.

      NAMED_BIND* Compile in code to use the Berkeley Inter-
                  net Name Domain (BIND) server  to  resolve
                  TCP/IP host names.

      NOTUNIX     If  you  are using a non-UNIX mail format,
                  you can set this flag to turn off  special
                  processing of UNIX-style "From " lines.

      USERDB*     Include the experimental Berkeley user in-
                  formation database package.  This  adds  a
                  new  level of local name expansion between
                  aliasing and forwarding.  It also uses the
                  NEWDB  package.  This may change in future
                  releases.

      The following options are normally turned on  in  per-
      operating-system clauses in conf.h.

      IDENTPROTO* Compile  in  the IDENT protocol as defined
                  in RFC 1413.  This  defaults  on  for  all
                  systems  except  Ultrix,  which apparently
                  has the interesting "feature" that when it
                  receives  a  "host unreachable" message it
                  closes all open connections to that  host.
                  Since some firewall gateways send this er-
                  ror code when you access  an  unauthorized
                  port  (such as 113, used by IDENT), Ultrix
                  cannot receive email from such hosts.

      SYSTEM5     Set all of the compilation parameters  ap-
                  propriate for System V.

      HASFLOCK*   Use Berkeley-style flock instead of System
                  V lockf to do file locking.   Due  to  the
                  highly  unusual  semantics of locks across
                  forks in lockf, this should always be used
                  if at all possible.

      HASINITGROUPS
                  Set  this  if  your  system  has the init-
                  groups() call (if you have multiple  group
                  support).   This is the default if SYSTEM5










Sendmail Installation and Operation Guide         SMM:08-161


                  is not defined or if you are on HPUX.

      HASUNAME    Set this if you have the  uname(2)  system
                  call  (or  corresponding library routine).
                  Set by default if SYSTEM5 is set.

      HASGETDTABLESIZE
                  Set this if you have the  getdtablesize(2)
                  system call.

      HASWAITPID  Set  this  if  you  have the haswaitpid(2)
                  system call.

      FAST_PID_RECYCLE
                  Set this if your system can possibly reuse
                  the same pid in the same second of time.

      SFS_TYPE    The mechanism that can be used to get file
                  system capacity information.   The  values
                  can  be one of SFS_USTAT (use the ustat(2)
                  syscall), SFS_4ARGS (use the four argument
                  statfs(2)  syscall),  SFS_VFS (use the two
                  argument   statfs(2)   syscall   including
                  <sys/vfs.h>), SFS_MOUNT (use the two argu-
                  ment    statfs(2)    syscall     including
                  <sys/mount.h>),  SFS_STATFS  (use  the two
                  argument   statfs(2)   syscall   including
                  <sys/statfs.h>),  SFS_STATVFS (use the two
                  argument   statfs(2)   syscall   including
                  <sys/statvfs.h>),  or  SFS_NONE (no way to
                  get this information).

      LA_TYPE     The load average type.   Details  are  de-
                  scribed below.

      The  are  several  built-in ways of computing the load
      average.  Sendmail tries to auto-configure them  based
      on  imperfect guesses; you can select one using the cc
      option -DLA_TYPE=type, where type is:

      LA_INT      The kernel stores the load average in  the
                  kernel  as an array of long integers.  The
                  actual values are scaled by a  factor  FS-
                  CALE (default 256).

      LA_SHORT    The  kernel stores the load average in the
                  kernel as an array of short integers.  The
                  actual  values  are scaled by a factor FS-
                  CALE (default 256).

      LA_FLOAT    The kernel stores the load average in  the
                  kernel  as  an  array  of double precision
                  floats.










SMM:08-162         Sendmail Installation and Operation Guide


      LA_MACH     Use MACH-style load averages.

      LA_SUBR     Call the getloadavg  routine  to  get  the
                  load average as an array of doubles.

      LA_ZERO     Always  return  zero  as the load average.
                  This is the fallback case.

      If type LA_INT, LA_SHORT, or  LA_FLOAT  is  specified,
      you  may  also need to specify _PATH_UNIX (the path to
      your system binary) and LA_AVENRUN (the  name  of  the
      variable  containing  the  load average in the kernel;
      usually "_avenrun" or "avenrun").

   6.3.  Configuration in sendmail/conf.c

           The following changes can be made in conf.c.

      6.3.1.  Built-in Header Semantics

              Not all header semantics are  defined  in  the
         configuration  file.  Header lines that should only
         be included by certain mailers (as  well  as  other
         more  obscure  semantics)  must be specified in the
         HdrInfo table in conf.c.  This table  contains  the
         header name (which should be in all lower case) and
         a set of header control  flags  (described  below),
         The flags are:

         H_ACHECK    Normally  when the check is made to see
                     if a header line is compatible  with  a
                     mailer, sendmail will not delete an ex-
                     isting line.   If  this  flag  is  set,
                     sendmail   will  delete  even  existing
                     header lines.  That is, if this bit  is
                     set  and  the mailer does not have flag
                     bits set that intersect  with  the  re-
                     quired mailer flags in the header defi-
                     nition in sendmail.cf, the header  line
                     is always deleted.

         H_EOH       If  this  header field is set, treat it
                     like a blank line, i.e., it will signal
                     the end of the header and the beginning
                     of the message text.

         H_FORCE     Add this header entry even if  one  ex-
                     isted  in  the  message  before.   If a
                     header entry does  not  have  this  bit
                     set,  sendmail  will  not  add  another
                     header line if a header  line  of  this
                     name  already existed.  This would nor-
                     mally be used to stamp the  message  by










Sendmail Installation and Operation Guide         SMM:08-163


                     everyone who handled it.

         H_TRACE     If  set,  this  is  a timestamp (trace)
                     field.  If the number of  trace  fields
                     in  a  message  exceeds a preset amount
                     the message is returned on the  assump-
                     tion that it has an aliasing loop.

         H_RCPT      If  set,  this field contains recipient
                     addresses.  This is used by the -t flag
                     to  determine who to send to when it is
                     collecting recipients from the message.

         H_FROM      This flag  indicates  that  this  field
                     specifies a sender.  The order of these
                     fields in the HdrInfo  table  specifies
                     sendmail's  preference  for which field
                     to return error messages to.

         H_ERRORSTO  Addresses in this header should receive
                     error messages.

         H_CTE       This  header  is a Content-Transfer-En-
                     coding header.

         H_CTYPE     This header is a Content-Type header.

         H_BCC       Strip the value from  the  header  (for
                     Bcc:).

         Let's look at a sample HdrInfo specification:
































SMM:08-164         Sendmail Installation and Operation Guide


             struct hdrinfo                    HdrInfo[] =
             {
                      /* originator fields, most to least significant  */
                 "resent-sender",              H_FROM,
                 "resent-from",                H_FROM,
                 "sender",                     H_FROM,
                 "from",                       H_FROM,
                 "full-name",                  H_ACHECK,
                 "errors-to",                  H_FROM|H_ERRORSTO,
                      /* destination fields */
                 "to",                         H_RCPT,
                 "resent-to",                  H_RCPT,
                 "cc",                         H_RCPT,
                 "bcc",                        H_RCPT|H_BCC,
                      /* message identification and control */
                 "message",                    H_EOH,
                 "text",                       H_EOH,
                      /* trace fields */
                 "received",                   H_TRACE|H_FORCE,
                      /* miscellaneous fields */
                 "content-transfer-encoding",  H_CTE,
                 "content-type",               H_CTYPE,

                 NULL,                         0,
             };

         This  structure  indicates that the "To:", "Resent-
         To:", and "Cc:" fields all  specify  recipient  ad-
         dresses.   Any  "Full-Name:"  field will be deleted
         unless the required mailer flag (indicated  in  the
         configuration  file)  is specified.  The "Message:"
         and "Text:" fields will terminate the header; these
         are  used  by  random dissenters around the network
         world.  The "Received:" field will always be added,
         and can be used to trace messages.

              There  are  a number of important points here.
         First, header fields are  not  added  automatically
         just  because  they  are  in the HdrInfo structure;
         they must be specified in the configuration file in
         order  to  be  added  to  the  message.  Any header
         fields mentioned in the configuration file but  not
         mentioned  in  the  HdrInfo  structure have default
         processing performed; that is, they are  added  un-
         less they were in the message already.  Second, the
         HdrInfo structure only specifies  cliched  process-
         ing;  certain headers are processed specially by ad
         hoc code regardless  of  the  status  specified  in
         HdrInfo.   For  example,  the "Sender:" and "From:"
         fields are always scanned on ARPANET mail to deter-













Sendmail Installation and Operation Guide         SMM:08-165


         mine  the  sender[24];  this is used to perform the
         "return  to  sender"  function.   The  "From:"  and
         "Full-Name:"  fields are used to determine the full
         name of the sender if possible; this is  stored  in
         the macro $x and used in a number of ways.

      6.3.2.  Restricting Use of Email

              If  it is necessary to restrict mail through a
         relay, the checkcompat  routine  can  be  modified.
         This routine is called for every recipient address.
         It returns an exit status indicating the status  of
         the message.  The status EX_OK accepts the address,
         EX_TEMPFAIL queues the message for a later try, and
         other  values  (commonly EX_UNAVAILABLE) reject the
         message.  It is up to checkcompat to print an error
         message  (using usrerr) if the message is rejected.
         For example, checkcompat could read:

             int
             checkcompat(to, e)
                 register ADDRESS *to;
                 register ENVELOPE *e;
             {
                 register STAB *s;

                 s = stab("private", ST_MAILER, ST_FIND);
                 if (s != NULL && e->e_from.q_mailer != LocalMailer &&
                     to->q_mailer == s->s_mailer)
                 {
                     usrerr("No private net mail allowed through this machine");
                     return (EX_UNAVAILABLE);
                 }
                 if (MsgSize > 50000 && bitnset(M_LOCALMAILER, to->q_mailer))
                 {
                     usrerr("Message too large for non-local delivery");
                     e->e_flags |= EF_NORETURN;
                     return (EX_UNAVAILABLE);
                 }
                 return (EX_OK);
             }

         This would reject messages greater than 50000 bytes
         unless  they  were local.  The EF_NORETURN flag can
         be set in e->e_flags to suppress the return of  the
         actual  body  of  the  message in the error return.
         The actual use of this routine is highly  dependent
         on the implementation, and use should be limited.
____________________
   [24]Actually, this is no longer true in SMTP; this infor-
mation is contained in the envelope.  The older ARPANET pro-
tocols did not completely distinguish envelope from header.











SMM:08-166         Sendmail Installation and Operation Guide


      6.3.3.  New Database Map Classes

              New  key maps can be added by creating a class
         initialization  function  and  a  lookup  function.
         These are then added to the routine setupmaps.

              The initialization function is called as

             xxx_map_init(MAP *map, char *args)

         The map is an internal data structure.  The args is
         a pointer to the portion of the configuration  file
         line  following the map class name; flags and file-
         names can be extracted from this  line.   The  ini-
         tialization  function  must  return true if it suc-
         cessfully opened the map, false otherwise.

              The lookup function is called as

             xxx_map_lookup(MAP *map, char buf[], char **av, int *statp)

         The map defines the map internally.   The  buf  has
         the input key.  This may be (and often is) used de-
         structively.  The av is a list of arguments  passed
         in  from  the  rewrite  line.   The lookup function
         should return a pointer to the new value.   If  the
         map  lookup  fails, *statp should be set to an exit
         status code; in particular, it  should  be  set  to
         EX_TEMPFAIL  if  recovery is to be attempted by the
         higher level code.

      6.3.4.  Queueing Function

              The routine shouldqueue is called to decide if
         a  message  should  be  queued or processed immedi-
         ately.  Typically this compares the message  prior-
         ity to the current load average.  The default defi-
         nition is:

             bool
             shouldqueue(pri, ctime)
                 long pri;
                 time_t ctime;
             {
                 if (CurrentLA < QueueLA)
                     return false;
                 return (pri > (QueueFactor / (CurrentLA - QueueLA + 1)));
             }

         If the current load average (global  variable  Cur-
         rentLA,  which  is  set  before  this  function  is
         called) is less than the low threshold load average
         (option  x,  variable QueueLA), shouldqueue returns










Sendmail Installation and Operation Guide         SMM:08-167


         false immediately (that is, it should  not  queue).
         If  the  current  load  average  exceeds  the  high
         threshold load  average  (option  X,  variable  Re-
         fuseLA),   shouldqueue  returns  true  immediately.
         Otherwise, it computes the function  based  on  the
         message  priority,  the  queue  factor  (option  q,
         global variable QueueFactor), and the  current  and
         threshold load averages.

              An  implementation  wishing to take the actual
         age of the message into account can  also  use  the
         ctime parameter, which is the time that the message
         was first submitted to sendmail.  Note that the pri
         parameter  is  already  weighted  by  the number of
         times the message has  been  tried  (although  this
         tends  to  lower  the  priority of the message with
         time); the expectation is that the ctime  would  be
         used  as an "escape clause" to ensure that messages
         are eventually processed.

      6.3.5.  Refusing Incoming SMTP Connections

              The function refuseconnections returns true if
         incoming  SMTP  connections should be refused.  The
         current implementation is based exclusively on  the
         current  load  average  and the refuse load average
         option (option X, global variable RefuseLA):

             bool
             refuseconnections()
             {
                 return (RefuseLA > 0 && CurrentLA >= RefuseLA);
             }

         A more clever implementation  could  look  at  more
         system resources.

      6.3.6.  Load Average Computation

              The routine getla returns the current load av-
         erage (as a rounded integer).  The distribution in-
         cludes  several  possible  implementations.  If you
         are porting to a new environment you  may  need  to
         add some new tweaks.[25]




____________________
   [25]If  you  do,  please  send  updates to sendmail@Send-
mail.ORG.












SMM:08-168         Sendmail Installation and Operation Guide


   6.4.  Configuration in sendmail/daemon.c

           The file sendmail/daemon.c contains a  number  of
      routines  that  are  dependent on the local networking
      environment.  The version supplied  assumes  you  have
      BSD style sockets.

           In  previous  releases,  we  recommended that you
      modify the routine maphostname if you wanted to gener-
      alize  $[  ...  $] lookups.  We now recommend that you
      create a new keyed map instead.

   6.5.  LDAP

           In this section we assume that sendmail has  been
      compiled with support for LDAP.

      6.5.1.  LDAP Recursion

              LDAP  Recursion allows you to add types to the
         search attributes on  an  LDAP  map  specification.
         The syntax is:

         -v ATTRIBUTE[:TYPE[:OBJECTCLASS[|OBJECTCLASS|...]]]


              The new TYPEs are:

         NORMAL    This attribute type specifies the  attri-
                   bute  to add to the results string.  This
                   is the default.

         DN        Any matches for this  attribute  are  ex-
                   pected  to have a value of a fully quali-
                   fied distinguished name.   sendmail  will
                   lookup  that  DN and apply the attributes
                   requested to the returned DN record.

         FILTER    Any matches for this  attribute  are  ex-
                   pected  to have a value of an LDAP search
                   filter.  sendmail will perform  a  lookup
                   with  the same parameters as the original
                   search but  replaces  the  search  filter
                   with the one specified here.

         URL       Any  matches  for  this attribute are ex-
                   pected to have a value of  an  LDAP  URL.
                   sendmail  will  perform  a lookup of that
                   URL and use  the  results  from  the  at-
                   tributes named in that URL.  Note however
                   that the search is done using the current
                   LDAP  connection,  regardless  of what is
                   specified as the scheme, LDAP  host,  and










Sendmail Installation and Operation Guide         SMM:08-169


                   LDAP port in the LDAP URL.

         Any  untyped  attributes  are considered NORMAL at-
         tributes as described above.

              The optional OBJECTCLASS  (|  separated)  list
         contains  the objectClass values for which that at-
         tribute applies.  If the list is given, the  attri-
         bute named will only be used if the LDAP record be-
         ing returned is a  member  of  that  object  class.
         Note  that  if  these new value attribute TYPEs are
         used in an AliasFile option setting, it  will  need
         to  be  double quoted to prevent sendmail from mis-
         parsing the colons.

              Note that LDAP recursion attributes  which  do
         not ultimately point to an LDAP record are not con-
         sidered an error.

         6.5.1.1.  Example

                 Since examples usually help  clarify,  here
            is  an  example  which  uses all four of the new
            types:

                O LDAPDefaultSpec=-h ldap.example.com -b dc=example,dc=com

                Kexample ldap
                         -z,
                         -k (&(objectClass=sendmailMTAAliasObject)(sendmailMTAKey=%0))
                         -v sendmailMTAAliasValue,mail:NORMAL:inetOrgPerson,
                            uniqueMember:DN:groupOfUniqueNames,
                            sendmailMTAAliasSearch:FILTER:sendmailMTAAliasObject,
                            sendmailMTAAliasURL:URL:sendmailMTAAliasObject


                 That definition specifies that:

             + Any value in a  sendmailMTAAliasValue  attri-
               bute  will  be added to the result string re-
               gardless of object class.
             + The mail attribute will be added to  the  re-
               sult string if the LDAP record is a member of
               the inetOrgPerson object class.
             + The uniqueMember attribute is a recursive at-
               tribute,   used  only  in  groupOfUniqueNames
               records, and should contain an LDAP DN point-
               ing  to another LDAP record.  The desire here
               is to return the mail  attribute  from  those
               DNs.
             + The   sendmailMTAAliasSearch   attribute  and
               sendmailMTAAliasURL are  both  used  only  if
               referenced in a sendmailMTAAliasObject.  They










SMM:08-170         Sendmail Installation and Operation Guide


               are both recursive, the first for a new  LDAP
               search string and the latter for an LDAP URL.

   6.6.  STARTTLS

           In  this section we assume that sendmail has been
      compiled with support for STARTTLS.  To  properly  un-
      derstand the use of STARTTLS in sendmail, it is neces-
      sary to understand at least some  basics  about  X.509
      certificates and public key cryptography.  This infor-
      mation can be found in books about SSL/TLS or  on  WWW
      sites, e.g., "https://www.OpenSSL.org/".

      6.6.1.  Certificates for STARTTLS

              When  acting  as  a  server, sendmail requires
         X.509 certificates to support STARTTLS: one as cer-
         tificate  for the server (ServerCertFile and corre-
         sponding private ServerKeyFile) at least  one  root
         CA  (CACertFile),  i.e., a certificate that is used
         to sign other certificates, and a path to a  direc-
         tory  which contains (zero or more) other CAs (CAC-
         ertPath).  The file specified  via  CACertFile  can
         contain  several  certificates  of CAs.  The DNs of
         these certificates are sent to  the  client  during
         the   TLS   handshake  (as  part  of  the  Certifi-
         cateRequest) as the list of acceptable  CAs.   How-
         ever,  do  not list too many root CAs in that file,
         otherwise the TLS handshake may fail; e.g.,

             error:14094417:SSL routines:SSL3_READ_BYTES:
             sslv3 alert illegal parameter:s3_pkt.c:964:SSL alert number 47

         You should probably put only the CA cert into  that
         file that signed your own cert(s), or at least only
         those you trust.   The  CACertPath  directory  must
         contain  the hashes of each CA certificate as file-
         names (or as links to them).  Symbolic links can be
         generated  with  the  following  two (Bourne) shell
         commands:

             C=FileName_of_CA_Certificate
             ln -s $C `openssl x509 -noout -hash < $C`.0

         A better way to do this is to use the c_rehash com-
         mand  that  is part of the OpenSSL distribution be-
         cause it handles subject hash collisions by  incre-
         menting the number in the suffix of the filename of
         the symbolic link, e.g., .0 to .1, and so  on.   An
         X.509  certificate is also required for authentica-
         tion in client mode (ClientCertFile and correspond-
         ing  private ClientKeyFile), however, sendmail will
         always use STARTTLS when offered by a server.   The










Sendmail Installation and Operation Guide         SMM:08-171


         client  and  server  certificates can be identical.
         Certificates can be obtained from a certificate au-
         thority  or  created with the help of OpenSSL.  The
         required format for certificates and  private  keys
         is  PEM.   To  allow for automatic startup of send-
         mail, private keys  (ServerKeyFile,  ClientKeyFile)
         must be stored unencrypted.  The keys are only pro-
         tected by  the  permissions  of  the  file  system.
         Never  make  a  private  key  available  to a third
         party.

              The  options  ClientCertFile,   ClientKeyFile,
         ServerCertFile, and ServerKeyFile can take a second
         file name, which must be separated from  the  first
         with  a  comma (note: do not use any spaces) to set
         up a second cert/key pair.  This  can  be  used  to
         have certs of different types, e.g., RSA and DSA.

      6.6.2.  PRNG for STARTTLS

              STARTTLS  requires a strong pseudo random num-
         ber generator (PRNG) to operate properly.   Depend-
         ing  on the TLS library you use, it may be required
         to explicitly initialize the PRNG with random data.
         OpenSSL  makes  use of /dev/urandom(4) if available
         (this corresponds  to  the  compile  flag  HASURAN-
         DOMDEV).   On  systems  which  lack this support, a
         random file must be specified  in  the  sendmail.cf
         file using the option RandFile.  It is strongly ad-
         vised to use the  "Entropy  Gathering  Daemon"  EGD
         from  Brian Warner on those systems to provide use-
         ful random data.  In this case,  sendmail  must  be
         compiled with the flag EGD, and the RandFile option
         must  point  to  the  EGD   socket.    If   neither
         /dev/urandom(4)  nor EGD are available, you have to
         make sure that useful random data is available  all
         the time in RandFile.  If the file hasn't been mod-
         ified in the last 10 minutes before it is  supposed
         to  be  used  by sendmail the content is considered
         obsolete.  One method for generating this file is:

             openssl rand -out /etc/mail/randfile -rand /path/to/file:...256

         See the OpenSSL documentation for more information.
         In  this case, the PRNG for TLS is only seeded with
         other random data if the  DontBlameSendmail  option
         InsufficientEntropy  is  set.   This is most likely
         not sufficient for certain actions,  e.g.,  genera-
         tion of (temporary) keys.

              Please  see the OpenSSL documentation or other
         sources for further information about certificates,
         their creation and their usage, the importance of a










SMM:08-172         Sendmail Installation and Operation Guide


         good PRNG, and other aspects of TLS.

   6.7.  Encoding of STARTTLS and AUTH related Macros

           Macros that contain  STARTTLS  and  AUTH  related
      data  which  comes  from  outside  sources,  e.g., all
      macros containing information from  certificates,  are
      encoded  to  avoid problems with non-printable or spe-
      cial characters.  The latter are '\', '<',  '>',  '(',
      ')',  '"',  '+', and ' '.  All of these characters are
      replaced by their value in hexadecimal with a  leading
      '+'.  For example:

          /C=US/ST=California/O=endmail.org/OU=private/CN=Darth Mail (Cert)/
          Email=darth+cert@endmail.org

      is encoded as:

          /C=US/ST=California/O=endmail.org/OU=private/
          CN=Darth+20Mail+20+28Cert+29/Email=darth+2Bcert@endmail.org

      (line breaks have been inserted for readability).  The
      macros  which  are  subject  to  this   encoding   are
      {cert_subject},  {cert_issuer},  {cn_subject}, {cn_is-
      suer}, as well as {auth_authen} and {auth_author}.

   6.8.  DANE

           Initial support for DANE (see  RFC  7672  et.al.)
      is  available  if sendmail is compiled with the option
      DANE.  Only TLSA RR 3-1-x (DANE-EE) is  currently  im-
      plemented.  The option

          O DANE=true

      enables  this feature at run time and it automatically
      adds use_dnssec and use_edns0 to

          O ResolverOptions

      This requires a (preferrably local) validating DNS re-
      solver which supports those options.

      If  the  client  finds  a usable TLSA RR and the check
      succeeds the macro ${verify} is set to  TRUSTED.   All
      non-DNS  maps  are  considered  secure  just  like DNS
      lookups with DNSSEC.  Be aware that the implementation
      might  not  handle all error conditions as required by
      the RFCs.  Moreover, TLSA RRs are not  looked  up  for
      some features, e.g., FallBackSmartHost.













Sendmail Installation and Operation Guide         SMM:08-173


   6.9.  EAI

           Experimental  support  for SMTPUTF8 (EAI, see RFC
      6530-6533) is available when the compile  time  option
      USE_EAI, (see also devtools/Site/site.config.m4.sample
      for other settings that might be needed), and  the  cf
      option  SMTPUTF8  are  used.   This  allows the use of
      UTF-8 for envelope addresses as  well  as  the  entire
      message.   DNS lookups are done using the A-label for-
      mat (Punycode) as required by the RFCs.  For all other
      interactions  with external programs and maps, the ac-
      tual value are  used,  i.e.,  no  conversions  between
      UTF-8  and  ASCII encodings are made.  This applies to
      the keys in map lookups, which might require to  spec-
      ify  both versions in a map; the data exchanged with a
      milter, i.e., each milter must be "8 bit clean";  mail
      delivery agents which must be able to handle 8 bit ad-
      dresses.  Some values must be ASCII as those are  used
      before  SMTPUTF8  support  can be requested, e.g., the
      macros $j and $m.  Please test and provide feedback.

   6.10.  MTA-STS

           Experimental support for SMTP MTA  Strict  Trans-
      port  Security  (MTA-STS,  see  RFC 8461) is available
      when using the compile time  option  _FFR_MTA_STS  (as
      well as some others, e.g., _FFR_TLS_ALTNAMES and obvi-
      ously STARTTLS), FEATURE(sts) (which  implicitly  sets
      the  cf  option StrictTransportSecurity), and postfix-
      mta-sts-resolver (see https://github.com/Snawoot/post-
      fix-mta-sts-resolver.git).

           Note:  this  implementation  uses a socket map to
      communicate with postfix-mta-sts-resolver and  handles
      only  the values returned by that program, which might
      not fully implement MTA-STS.

           If both DANE and MTA-STS are enabled  and  avail-
      able for the receiving domain, DANE is used because it
      offers a much higher level of security.

7.  ACKNOWLEDGEMENTS

        I've worked on sendmail for many years, and many em-
   ployers  have  been  remarkably  patient about letting me
   work on a large project that was not part of my  official
   job.   This  includes  time  on the INGRES Project at the
   University of California at Berkeley, at Britton Lee, and
   again on the Mammoth and Titan Projects at Berkeley.

        Much of the second wave of improvements resulting in
   version 8.1 should be credited to Bryan Costales  of  the
   International  Computer  Science Institute.  As he passed










SMM:08-174         Sendmail Installation and Operation Guide


   me drafts of his book on sendmail I was inspired to start
   working  on  things  again.   Bryan was also available to
   bounce ideas off of.

        Gregory Neil Shapiro of Worcester Polytechnic Insti-
   tute  has  become  instrumental in all phases of sendmail
   support and development, and was largely responsible  for
   getting versions 8.8 and 8.9 out the door.

        Many,  many  people  contributed  chunks of code and
   ideas to sendmail.  It has proven to be a  group  network
   effort.   Version  8  in  particular was a group project.
   The following people and organizations made notable  con-
   tributions:

       Claus Assmann
       John Beck, Hewlett-Packard & Sun Microsystems
       Keith Bostic, CSRG, University of California, Berkeley
       Andrew Cheng, Sun Microsystems
       Michael J. Corrigan, University of California, San Diego
       Bryan Costales, International Computer Science Institute & InfoBeat
       Par (Pell) Emanuelsson
       Craig Everhart, Transarc Corporation
       Per Hedeland, Ericsson
       Tom Ivar Helbekkmo, Norwegian School of Economics
       Kari Hurtta, Finnish Meteorological Institute
       Allan E. Johannesen, WPI
       Jonathan Kamens, OpenVision Technologies, Inc.
       Takahiro Kanbe, Fuji Xerox Information Systems Co., Ltd.
       Brian Kantor, University of California, San Diego
       John Kennedy, Cal State University, Chico
       Murray S. Kucherawy, HookUp Communication Corp.
       Bruce Lilly, Sony U.S.
       Karl London
       Motonori Nakamura, Ritsumeikan University & Kyoto University
       John Gardiner Myers, Carnegie Mellon University
       Neil Rickert, Northern Illinois University
       Gregory Neil Shapiro, WPI
       Eric Schnoebelen, Convex Computer Corp.
       Eric Wassenaar, National Institute for Nuclear and High Energy Physics, Amsterdam
       Randall Winchester, University of Maryland
       Christophe Wolfhugel, Pasteur Institute & Herve Schauer Consultants (Paris)
       Exactis.com, Inc.

   I apologize for anyone I have omitted, misspelled, misat-
   tributed, or otherwise missed.  At this point, I  suspect
   that at least a hundred people have contributed code, and
   many more have contributed ideas, comments,  and  encour-
   agement.  I've tried to list them in the RELEASE_NOTES in
   the distribution directory.  I appreciate their contribu-
   tion as well.












Sendmail Installation and Operation Guide         SMM:08-175


        Special thanks are reserved for Michael Corrigan and
   Christophe Wolfhugel, who besides being wonderful  guinea
   pigs  and contributors have also consented to be added to
   the ``sendmail@Sendmail.ORG'' list and, by answering  the
   bulk of the questions sent to that list, have freed me up
   to do other work.




























































                          APPENDIX  A


                      COMMAND LINE FLAGS




     Arguments must  be  presented  with  flags  before  ad-
dresses.  The flags are:

-Ax       Select  an  alternative  .cf  file which is either
          sendmail.cf for -Am or submit.cf for -Ac.  By  de-
          fault  the  .cf file is chosen based on the opera-
          tion mode.  For -bm (default), -bs, and -t  it  is
          submit.cf if it exists, for all others it is send-
          mail.cf.

-bx       Set operation mode to x.  Operation modes are:

              m   Deliver mail (default)
              s   Speak SMTP on input side
              a*  ``Arpanet'' mode (get envelope sender information from header)
              C   Check the configuration file
              d   Run as a daemon in background
              D   Run as a daemon in foreground
              t   Run in test mode
              v   Just verify addresses, don't collect or deliver
              i   Initialize the alias database
              p   Print the mail queue
              P   Print overview over the mail queue (requires shared memory)
              h   Print the persistent host status database
              H   Purge expired entries from the persistent host status database


-Btype    Indicate body type.

-Cfile    Use a different configuration file.  Sendmail runs
          as  the invoking user (rather than root) when this
          flag is specified.

-D logfile
          Send debugging output to the indicated logfile in-
          stead of stdout.

-dlevel   Set debugging level.

-f addr   The  envelope sender address is set to addr.  This
          address may also be used in the  From:  header  if
____________________
   *Deprecated.




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Sendmail Installation and Operation Guide         SMM:08-177


          that  header is missing during initial submission.
          The envelope sender address is used as the recipi-
          ent for delivery status notifications and may also
          appear in a Return-Path: header.

-F name   Sets the full name of this user to name.

-G        When accepting messages via the command line,  in-
          dicate  that  they are for relay (gateway) submis-
          sion.  sendmail may complain  about  syntactically
          invalid  messages,  e.g.,  unqualified host names,
          rather than fixing them when  this  flag  is  set.
          sendmail  will not do any canonicalization in this
          mode.

-h cnt    Sets the "hop count" to cnt.  This represents  the
          number of times this message has been processed by
          sendmail (to the extent that it  is  supported  by
          the underlying networks).  Cnt is incremented dur-
          ing processing, and if  it  reaches  MAXHOP  (cur-
          rently  25)  sendmail throws away the message with
          an error.

-L tag    Sets the identifier used for  syslog.   Note  that
          this identifier is set as early as possible.  How-
          ever, sendmail may be used if problems  arise  be-
          fore the command line arguments are processed.

-n        Don't do aliasing or forwarding.

-N notifications
          Tag  all addresses being sent as wanting the indi-
          cated notifications, which consists  of  the  word
          "NEVER"  or  a  comma-separated list of "SUCCESS",
          "FAILURE", and "DELAY"  for  successful  delivery,
          failure,  and  a  message that is stuck in a queue
          somewhere.  The default is "FAILURE,DELAY".

-r addr   An obsolete form of -f.

-oxvalue  Set option x to the specified  value.   These  op-
          tions are described in Section 5.6.

-Ooption=value
          Set  option  to the specified value (for long form
          option names).  These  options  are  described  in
          Section 5.6.

-Mxvalue  Set macro x to the specified value.

-pprotocol
          Set the sending protocol.  Programs are encouraged
          to set this.  The protocol field  can  be  in  the










SMM:08-178         Sendmail Installation and Operation Guide


          form  protocol:host to set both the sending proto-
          col and sending host.  For example, "-pUUCP:uunet"
          sets  the sending protocol to UUCP and the sending
          host to uunet.  (Some existing programs use -oM to
          set  the r and s macros; this is equivalent to us-
          ing -p.)

-qtime    Try to process the queued up mail.  If the time is
          given,  sendmail  will start one or more processes
          to run through the queue(s) at the specified  time
          interval  to  deliver  queued  mail; otherwise, it
          only runs once.  Each of these processes acts on a
          workgroup.   These  processes  are  also  known as
          workgroup processes  or  WGP's  for  short.   Each
          workgroup  is responsible for controlling the pro-
          cessing of one or  more  queues;  workgroups  help
          manage  the  use  of system resources by sendmail.
          Each workgroup may have one or more children  con-
          currently  processing queues depending on the set-
          ting of MaxQueueChildren.

-qptime   Similar to -q with a time  argument,  except  that
          instead  of  periodically  starting WGP's sendmail
          starts persistent  WGP's  that  alternate  between
          processing queues and sleeping.  The sleep time is
          specified by the time argument; it defaults  to  1
          second, except that a WGP always sleeps at least 5
          seconds if their queues were empty in the previous
          run.   Persistent processes are managed by a queue
          control process (QCP).   The  QCP  is  the  parent
          process  of  the WGP's.  Typically the QCP will be
          the sendmail daemon (when started with -bd or -bD)
          or  a  special process (named Queue control) (when
          started without -bd or -bD).  If a persistent  WGP
          ceases  to  be  active for some reason another WGP
          will be started by the QCP for the same  workgroup
          in  most  cases.  When  a  persistent WGP has core
          dumped, the debug  flag  no_persistent_restart  is
          set  or  the  specific  persistent  WGP  has  been
          restarted too many times already then the WGP will
          not  be started again and a message will be logged
          to this effect.   To  stop  (SIGTERM)  or  restart
          (SIGHUP)  persistent  WGP's the appropriate signal
          should be sent to the QCP. The QCP will  propagate
          the  signal to all of the WGP's and if appropriate
          restart the persistent WGP's.

-qGname   Run the jobs in the queue group name once.

-q[!]Xstring
          Run the queue once, limiting  the  jobs  to  those
          matching  Xstring.   The  key letter X can be I to
          limit based on queue identifier, R to limit  based










Sendmail Installation and Operation Guide         SMM:08-179


          on  recipient, S to limit based on sender, or Q to
          limit based on quarantine reason  for  quarantined
          jobs.   A particular queued job is accepted if one
          of the corresponding attributes contains the indi-
          cated  string.   The  optional ! character negates
          the condition tested.  Multiple -qX flags are per-
          mitted,  with  items  with  the  same  key  letter
          "or'ed" together, and  items  with  different  key
          letters "and'ed" together.

-Q[reason]
          Quarantine  normal queue items with the given rea-
          son or unquarantine quarantined queue items if  no
          reason  is  given.   This should only be used with
          some sort of item matching using  -q[!]Xstring  as
          described above.

-R ret    What  information you want returned if the message
          bounces; ret can be "HDRS"  for  headers  only  or
          "FULL"  for  headers plus body.  This is a request
          only; the other end is not required to  honor  the
          parameter.   If  "HDRS" is specified local bounces
          also return only the headers.

-t        Read the  header  for  "To:",  "Cc:",  and  "Bcc:"
          lines, and send to everyone listed in those lists.
          The "Bcc:" line will be  deleted  before  sending.
          Any  addresses  in  the  argument  vector  will be
          deleted from the send list.

-U        This option is required when  sending  mail  using
          UTF-8;  it sets the "SMTPUTF8" argument for "MAIL"
          command.  Only available if "EAI" support  is  en-
          abled, and the "SMTPUTF8" option is set.

-V envid  The indicated envid is passed with the envelope of
          the message and returned if the message bounces.

-X logfile
          Log all traffic in and out of sendmail in the  in-
          dicated  logfile  for  debugging  mailer problems.
          This produces a  lot  of  data  very  quickly  and
          should be used sparingly.

     There  are a number of options that may be specified as
primitive flags.  These are the e,  i,  m,  and  v  options.
Also, the f option may be specified as the -s flag.  The DSN
related options "-N", "-R", and  "-V"  have  no  effects  on
sendmail running as daemon.

















                        APPENDIX  B


                     QUEUE FILE FORMATS




     This  appendix describes the format of the queue files.
These files live in a queue directory.  The  individual  qf,
hf, Qf, df, and xf files may be stored in separate qf/, df/,
and xf/ subdirectories if they are present in the queue  di-
rectory.

     All  queue  files  have  the name ttYMDhmsNNppppp where
YMDhmsNNppppp is the id for this message and  the  tt  is  a
type.  The individual letters in the id are:

Y    Encoded year

M    Encoded month

D    Encoded day

h    Encoded hour

m    Encoded minute

s    Encoded second

NN   Encoded envelope number

ppppp
     At least five decimal digits of the process ID

     All files with the same id collectively define one mes-
sage.  Due to the use  of  memory-buffered  files,  some  of
these files may never appear on disk.

     The types are:

qf   The  queue control file.  This file contains the infor-
     mation necessary to process the job.

hf   The same as a queue control file, but for a quarantined
     queue job.

df   The data file.  The message body (excluding the header)
     is kept in this file.  Sometimes the  df  file  is  not
     stored  in  the  same directory as the qf file; in this
     case, the qf file contains a `d' record which names the
     queue directory that contains the df file.



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Sendmail Installation and Operation Guide         SMM:08-181


tf   A temporary file.  This is an image of the qf file when
     it is being rebuilt.  It should be renamed to a qf file
     very quickly.

xf   A  transcript  file, existing during the life of a ses-
     sion showing everything that happens during  that  ses-
     sion.  Sometimes the xf file must be generated before a
     queue group has been selected; in  this  case,  the  xf
     file will be stored in a directory of the default queue
     group.

Qf   A ``lost'' queue control file.  sendmail renames  a  qf
     file to Qf if there is a severe (configuration) problem
     that  cannot  be  solved  without  human  intervention.
     Search  the logfile for the queue file id to figure out
     what happened.  After you resolved the problem, you can
     rename the Qf file to qf and send it again.

     The  queue  control  file  is structured as a series of
lines each beginning with a code letter; the file  must  end
with  a line containing only a single dot.  The lines are as
follows:

V    The version number of the queue file  format,  used  to
     allow new sendmail binaries to read queue files created
     by older versions.  Defaults to version zero.  Must  be
     the  first  line  of the file if present.  For 8.13 and
     later the version number is 8.

A    The information given by the  AUTH=  parameter  of  the
     SMTP  MAIL command or $f@$j if sendmail has been called
     directly.

H    A header definition.  There may be any number of  these
     lines.   The order is important: they represent the or-
     der in the final message.  These use the same syntax as
     header definitions in the configuration file.

C    The   controlling   address.    The   syntax   is  "lo-
     caluser:aliasname".  Recipient addresses following this
     line  will be flagged so that deliveries will be run as
     the localuser (a user name from the /etc/passwd  file);
     aliasname  is  the  name  of the alias that expanded to
     this address (used for printing messages).

q    The quarantine reason for quarantined queue items.

Q    The ``original recipient'',  specified  by  the  ORCPT=
     field  in  an  ESMTP transaction.  Used exclusively for
     Delivery Status Notifications.  It applies only to  the
     following `R' line.












SMM:08-182         Sendmail Installation and Operation Guide


r    The  ``final recipient'' used for Delivery Status Noti-
     fications.  It applies only to the following `R' line.

R    A recipient address.  This will normally be  completely
     aliased, but is actually realiased when the job is pro-
     cessed.  There will be one  line  for  each  recipient.
     Version  1 qf files also include a leading colon-termi-
     nated list of flags, some of which are `S' to return  a
     message  on  successful final delivery, `F' to return a
     message on failure, `D' to return a message if the mes-
     sage  is  delayed,  `N' to suppress returning the body,
     and `P' to declare this as a ``primary'' (command  line
     or SMTP-session) address.

S    The  sender  address.   There  may only be one of these
     lines.

T    The job creation time.  This is used to compute when to
     time out the job.

P    The  current  message  priority.  This is used to order
     the queue.  Higher numbers mean lower priorities.   The
     priority changes as the message sits in the queue.  The
     initial priority depends on the message class  and  the
     size of the message.

M    A  message.  This line is printed by the mailq command,
     and is generally used to store status information.   It
     can contain any text.

F    Flag bits, represented as one letter per flag.  Defined
     flag bits are r indicating that this is a response mes-
     sage  and  w indicating that a warning message has been
     sent announcing that the mail has been delayed.   Other
     flag  bits  are:  8:  the body contains 8bit data, b: a
     Bcc: header should be removed, d: the mail has RET  pa-
     rameters  (see  RFC  1894),  n: the body of the message
     should not be returned in case of an error, s: the  en-
     velope has been split.

N    The total number of delivery attempts.

K    The time (as seconds since January 1, 1970) of the last
     delivery attempt.

d    If the df file is in a different directory than the  qf
     file,  then a `d' record is present, specifying the di-
     rectory in which the df file resides.

I    The i-number of the data file; this can be used to  re-
     cover your mail queue after a disastrous disk crash.












Sendmail Installation and Operation Guide         SMM:08-183


$    A  macro  definition.  The values of certain macros are
     passed through to the queue run phase.

B    The body type.  The remainder of the  line  is  a  text
     string  defining the body type.  If this field is miss-
     ing, the body type is assumed to be "undefined" and  no
     special  processing  is  attempted.   Legal  values are
     "7BIT" and "8BITMIME".

Z    The original envelope id (from the ESMTP  transaction).
     For Deliver Status Notifications only.

     As  an  example,  the following is a queue file sent to
"eric@mammoth.Berkeley.EDU"  and   "bostic@okeeffe.CS.Berke-
ley.EDU"[1]:

    V4
    T711358135
    K904446490
    N0
    P2100941
    $_eric@localhost
    ${daemon_flags}
    Seric
    Ceric:100:1000:sendmail@vangogh.CS.Berkeley.EDU
    RPFD:eric@mammoth.Berkeley.EDU
    RPFD:bostic@okeeffe.CS.Berkeley.EDU
    H?P?Return-path: <^g>
    H??Received: by vangogh.CS.Berkeley.EDU (5.108/2.7) id AAA06703;
        Fri, 17 Jul 1992 00:28:55 -0700
    H??Received: from mail.CS.Berkeley.EDU by vangogh.CS.Berkeley.EDU (5.108/2.7)
        id AAA06698; Fri, 17 Jul 1992 00:28:54 -0700
    H??Received: from [128.32.31.21] by mail.CS.Berkeley.EDU (5.96/2.5)
        id AA22777; Fri, 17 Jul 1992 03:29:14 -0400
    H??Received: by foo.bar.baz.de (5.57/Ultrix3.0-C)
        id AA22757; Fri, 17 Jul 1992 09:31:25 GMT
    H?F?From: eric@foo.bar.baz.de (Eric Allman)
    H?x?Full-name: Eric Allman
    H??Message-id: <9207170931.AA22757@foo.bar.baz.de>
    H??To: sendmail@vangogh.CS.Berkeley.EDU
    H??Subject: this is an example message
    .

This  shows  the person who sent the message, the submission
time (in seconds since January 1, 1970), the message  prior-
ity,  the message class, the recipients, and the headers for
the message.
____________________
   [1]This  example is contrived and probably inaccurate for
your environment.  Glance over it to get  an  idea;  nothing
can replace looking at what your own system generates.















                        APPENDIX  C


                  SUMMARY OF SUPPORT FILES




     This is a summary of the support  files  that  sendmail
creates or generates.  Many of these can be changed by edit-
ing the sendmail.cf file; check there  to  find  the  actual
pathnames.

/usr/sbin/sendmail
          The binary of sendmail.

/usr/bin/newaliases
          A  link  to  /usr/sbin/sendmail;  causes the alias
          database to be rebuilt.  Running this  program  is
          completely  equivalent  to giving sendmail the -bi
          flag.

/usr/bin/mailq
          Prints a listing of the mail queue.  This  program
          is equivalent to using the -bp flag to sendmail.

/etc/mail/sendmail.cf
          The configuration file, in textual form.

/etc/mail/helpfile
          The SMTP help file.

/etc/mail/statistics
          A statistics file; need not be present.

/etc/mail/sendmail.pid
          Created in daemon mode; it contains the process id
          of the current SMTP daemon.  If you  use  this  in
          scripts;  use  ``head  -1''  to get just the first
          line; the second line contains  the  command  line
          used  to  invoke the daemon, and later versions of
          sendmail may add more  information  to  subsequent
          lines.

/etc/mail/aliases
          The textual version of the alias file.

/etc/mail/aliases.db
          The alias file in hash(3) format.

/etc/mail/aliases.{pag,dir}
          The alias file in ndbm(3) format.



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Sendmail Installation and Operation Guide         SMM:08-185


/var/spool/mqueue
          The  directory in which the mail queue(s) and tem-
          porary files reside.

/var/spool/mqueue/qf*
          Control (queue) files for messages.

/var/spool/mqueue/df*
          Data files.

/var/spool/mqueue/tf*
          Temporary versions of the qf  files,  used  during
          queue file rebuild.

/var/spool/mqueue/xf*
          A transcript of the current session.















































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          replace it with a blank sheet for double-sided output.












































Sendmail Installation and Operation Guide           SMM:08-3


                          TABLE OF CONTENTS

1.  BASIC INSTALLATION ................................    7
   1.1.  Compiling Sendmail ...........................    7
      1.1.1.  Tweaking the Build Invocation ...........    7
      1.1.2.  Creating a Site Configuration File ......    8
      1.1.3.  Tweaking the Makefile ...................    8
      1.1.4.  Compilation and installation ............    9
   1.2.  Configuration Files ..........................   10
   1.3.  Details of Installation Files ................   12
      1.3.1.  /usr/sbin/sendmail ......................   12
      1.3.2.  /etc/mail/sendmail.cf ...................   12
      1.3.3.  /etc/mail/submit.cf .....................   13
      1.3.4.  /usr/bin/newaliases .....................   13
      1.3.5.  /usr/bin/hoststat .......................   13
      1.3.6.  /usr/bin/purgestat ......................   13
      1.3.7.  /var/spool/mqueue .......................   14
      1.3.8.  /var/spool/clientmqueue .................   14
      1.3.9.  /var/spool/mqueue/.hoststat .............   15
      1.3.10.  /etc/mail/aliases* .....................   15
      1.3.11.  /etc/rc or /etc/init.d/sendmail ........   15
      1.3.12.  /etc/mail/helpfile .....................   16
      1.3.13.  /etc/mail/statistics ...................   16
      1.3.14.  /usr/bin/mailq .........................   16
      1.3.15.  sendmail.pid ...........................   18
      1.3.16.  Map Files ..............................   18
2.  NORMAL OPERATIONS .................................   19
   2.1.  The System Log ...............................   19
      2.1.1.  Format ..................................   19
      2.1.2.  Levels ..................................   20
   2.2.  Dumping State ................................   21
   2.3.  The Mail Queues ..............................   21
      2.3.1.  Queue Groups and Queue Directories ......   21
      2.3.2.  Queue Runs ..............................   22
      2.3.3.  Manual Intervention .....................   23
      2.3.4.  Printing the queue ......................   23
      2.3.5.  Forcing the queue .......................   24
      2.3.6.  Quarantined Queue Items .................   25
   2.4.  Disk Based Connection Information ............   26
   2.5.  The Service Switch ...........................   27
   2.6.  The Alias Database ...........................   28
      2.6.1.  Rebuilding the alias database ...........   30
      2.6.2.  Potential problems ......................   30
      2.6.3.  List owners .............................   31
   2.7.  User Information Database ....................   31
   2.8.  Per-User Forwarding (.forward Files) .........   32
   2.9.  Special Header Lines .........................   32
      2.9.1.  Errors-To: ..............................   32
      2.9.2.  Apparently-To: ..........................   33
      2.9.3.  Precedence ..............................   33
   2.10.  IDENT Protocol Support ......................   33
3.  ARGUMENTS .........................................   34
   3.1.  Queue Interval ...............................   34










SMM:08-4           Sendmail Installation and Operation Guide


   3.2.  Daemon Mode ..................................   35
   3.3.  Forcing the Queue ............................   35
   3.4.  Debugging ....................................   36
   3.5.  Changing the Values of Options ...............   37
   3.6.  Trying a Different Configuration File ........   37
   3.7.  Logging Traffic ..............................   38
   3.8.  Testing Configuration Files ..................   38
   3.9.  Persistent Host Status Information ...........   40
4.  TUNING ............................................   40
   4.1.  Timeouts .....................................   41
      4.1.1.  Queue interval ..........................   41
      4.1.2.  Read timeouts ...........................   41
      4.1.3.  Message timeouts ........................   44
   4.2.  Forking During Queue Runs ....................   46
   4.3.  Queue Priorities .............................   46
   4.4.  Load Limiting ................................   47
   4.5.  Resource Limits ..............................   47
   4.6.   Measures against Denial of Service Attacks
      .................................................   48
   4.7.  Delivery Mode ................................   48
   4.8.  Log Level ....................................   49
   4.9.  File Modes ...................................   50
      4.9.1.  To suid or not to suid?  ................   50
      4.9.2.  Turning off security checks .............   51
   4.10.  Connection Caching ..........................   55
   4.11.  Name Server Access ..........................   55
   4.12.  Moving the Per-User Forward Files ...........   57
   4.13.  Free Space ..................................   58
   4.14.  Maximum Message Size ........................   58
   4.15.  Privacy Flags ...............................   58
   4.16.  Send to Me Too ..............................   59
5.  THE WHOLE SCOOP ON THE CONFIGURATION FILE .........   59
   5.1.  R and S -- Rewriting Rules ...................   59
      5.1.1.  The left hand side ......................   60
      5.1.2.  The right hand side .....................   61
      5.1.3.  Semantics of rewriting rule sets ........   63
      5.1.4.  Ruleset hooks ...........................   64
         5.1.4.1.  check_relay ........................   65
         5.1.4.2.  check_mail .........................   65
         5.1.4.3.  check_rcpt .........................   65
         5.1.4.4.  check_data .........................   65
         5.1.4.5.  check_other ........................   65
         5.1.4.6.  check_compat .......................   66
         5.1.4.7.  check_eoh ..........................   66
         5.1.4.8.  check_eom ..........................   67
         5.1.4.9.  check_etrn .........................   67
         5.1.4.10.  check_expn ........................   67
         5.1.4.11.  check_vrfy ........................   68
         5.1.4.12.  clt_features ......................   68
         5.1.4.13.  trust_auth ........................   68
         5.1.4.14.  tls_client ........................   68
         5.1.4.15.  tls_server ........................   68
         5.1.4.16.  tls_rcpt ..........................   69










Sendmail Installation and Operation Guide           SMM:08-5


         5.1.4.17.  srv_features ......................   69
         5.1.4.18.  try_tls ...........................   70
         5.1.4.19.        tls_srv_features       and
            tls_clt_features
                 ......................................   70
         5.1.4.20.  authinfo ..........................   72
         5.1.4.21.  queuegroup ........................   72
         5.1.4.22.  greet_pause .......................   72
      5.1.5.  IPC mailers .............................   73
   5.2.  D -- Define Macro ............................   74
   5.3.  C and F -- Define Classes ....................   86
   5.4.  M -- Define Mailer ...........................   88
   5.5.  H -- Define Header ...........................   97
   5.6.  O -- Set Option ..............................   98
   5.7.  P -- Precedence Definitions ..................  133
   5.8.  V -- Configuration Version Level .............  134
   5.9.  K -- Key File Declaration ....................  136
   5.10.  Q -- Queue Group Declaration ................  149
   5.11.  X -- Mail Filter (Milter) Definitions .......  151
   5.12.  The User Database ...........................  152
      5.12.1.  Structure of the user database .........  153
      5.12.2.  User database semantics ................  154
      5.12.3.  Creating the database[23] ..............  155
6.  OTHER CONFIGURATION ...............................  155
   6.1.  Parameters in devtools/OS/$oscf ..............  155
      6.1.1.  For Future Releases .....................  157
   6.2.  Parameters in sendmail/conf.h ................  157
   6.3.  Configuration in sendmail/conf.c .............  162
      6.3.1.  Built-in Header Semantics ...............  162
      6.3.2.  Restricting Use of Email ................  165
      6.3.3.  New Database Map Classes ................  166
      6.3.4.  Queueing Function .......................  166
      6.3.5.  Refusing Incoming SMTP Connections ......  167
      6.3.6.  Load Average Computation ................  167
   6.4.  Configuration in sendmail/daemon.c ...........  168
   6.5.  LDAP .........................................  168
      6.5.1.  LDAP Recursion ..........................  168
         6.5.1.1.  Example ............................  169
   6.6.  STARTTLS .....................................  170
      6.6.1.  Certificates for STARTTLS ...............  170
      6.6.2.  PRNG for STARTTLS .......................  171
   6.7.   Encoding  of  STARTTLS  and  AUTH  related
      Macros ..........................................  172
   6.8.  DANE .........................................  172
   6.9.  EAI ..........................................  173
   6.10.  MTA-STS .....................................  173
7.  ACKNOWLEDGEMENTS ..................................  173
Appendix A.  COMMAND LINE FLAGS .......................  176
Appendix B.  QUEUE FILE FORMATS .......................  180
Appendix C.  SUMMARY OF SUPPORT FILES .................  184













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