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       master - Postfix master process configuration file format


       The  Postfix  mail  system  is  implemented by small number of (mostly)
       client commands that are invoked by users, and by a  larger  number  of
       services that run in the background.

       Postfix  services are implemented by daemon processes. These run in the
       background under control  of  the  master(8)  process.   The
       configuration  file defines how a client program connects to a service,
       and what daemon program runs when a service is requested.  Most  daemon
       processes  are  short-lived  and  terminate  voluntarily  after serving
       max_use clients, or after inactivity for  max_idle  or  more  units  of

       All  daemons  specified here must speak a Postfix-internal protocol. In
       order to execute non-Postfix software  use  the  local(8),  pipe(8)  or
       spawn(8)  services,  or  run  the  server  under control by inetd(8) or

       After changing you must execute "postfix  reload"  to  reload
       the configuration.


       The general format of the file is as follows:

       ·      Each  logical  line  defines  a  single  Postfix  service.  Each
              service is identified by its name and type as  described  below.
              When multiple lines specify the same service name and type, only
              the last one is remembered.  Otherwise, the order  of
              service definitions does not matter.

       ·      Empty  lines and whitespace-only lines are ignored, as are lines
              whose first non-whitespace character is a ‘#’.

       ·      A logical line starts with  non-whitespace  text.  A  line  that
              starts with whitespace continues a logical line.

       Each  logical  line  consists  of eight fields separated by whitespace.
       These are described below in the order as they appear in the

       Where  applicable  a  field  of  "-" requests that the built-in default
       value be used. For boolean fields specify "y" or "n"  to  override  the
       default value.

       Service name
              The service name syntax depends on the service type as described

       Service type
              Specify one of the following service types:

              inet   The service listens on a TCP/IP socket and is  accessible
                     via the network.

                     The  service name is specified as host:port, denoting the
                     host  and  port  on  which  new  connections  should   be
                     accepted.  The  host  part  (and  colon)  may be omitted.
                     Either host or port may be given in symbolic  form  (host
                     or  service  name) or in numeric form (IP address or port
                     number).  Host information may be enclosed  inside  "[]",
                     but this form is not necessary.

                     Examples:  a  service  named  or ::1:smtp
                     receives mail via the  loopback  interface  only;  and  a
                     service named 10025 accepts connections on TCP port 10025
                     via all interfaces configured  with  the  inet_interfaces

                     Note:   with   Postfix  version  2.2  and  later  specify
                     "inet_interfaces = loopback-only" in, instead  of
                     hard-coding  loopback IP address information in
                     or in

              unix   The service  listens  on  a  UNIX-domain  socket  and  is
                     accessible for local clients only.

                     The  service  name  is a pathname relative to the Postfix
                     queue   directory   (pathname   controlled    with    the
                     queue_directory configuration parameter in

                     On  Solaris  systems  the  unix  type is implemented with
                     streams sockets.

              fifo   The service  listens  on  a  FIFO  (named  pipe)  and  is
                     accessible for local clients only.

                     The  service  name  is a pathname relative to the Postfix
                     queue   directory   (pathname   controlled    with    the
                     queue_directory configuration parameter in

              pass   The service listens on a UNIX-domain socket, receives one
                     open connection (file descriptor passing) per  connection
                     request, and is accessible to local clients only.

                     The  service  name  is a pathname relative to the Postfix
                     queue   directory   (pathname   controlled    with    the
                     queue_directory configuration parameter in

                     This feature is available as of Postfix version 2.5.

       Private (default: y)
              Whether  or  not  access  is  restricted  to  the  mail  system.
              Internet (type inet) services can’t be private.

       Unprivileged (default: y)
              Whether the service runs with root privileges or as the owner of
              the  Postfix  system  (the  owner  name  is  controlled  by  the
              mail_owner configuration variable in the file).

              The local(8), pipe(8), spawn(8), and virtual(8) daemons  require

       Chroot (default: y)
              Whether  or  not  the  service  runs  chrooted to the mail queue
              directory  (pathname  is  controlled  by   the   queue_directory
              configuration variable in the file).

              Chroot  should not be used with the local(8), pipe(8), spawn(8),
              and virtual(8) daemons.  Although the proxymap(8) server can run
              chrooted,  doing  so  defeats most of the purpose of having that
              service in the first place.

              The files  in  the  examples/chroot-setup  subdirectory  of  the
              Postfix  source archive show set up a Postfix chroot environment
              on a variety of systems. See also BASIC_CONFIGURATION_README for
              issues related to running daemons chrooted.

       Wake up time (default: 0)
              Automatically  wake  up  the  named  service after the specified
              number of seconds. The wake up is implemented by  connecting  to
              the  service  and  sending a wake up request.  A ? at the end of
              the wake-up time field requests that no wake up events  be  sent
              before  the  first  time  a  service  is used.  Specify 0 for no
              automatic wake up.

              The pickup(8), qmgr(8) and flush(8) daemons require  a  wake  up

       Process limit (default: $default_process_limit)
              The  maximum  number  of processes that may execute this service
              simultaneously. Specify 0 for no process count limit.

              NOTE: Some Postfix services must  be  configured  as  a  single-
              process service (for example, qmgr(8)) and some services must be
              configured with no  process  limit  (for  example,  cleanup(8)).
              These limits must not be changed.

       Command name + arguments
              The  command to be executed.  Characters that are special to the
              shell such as ">" or "|"  have  no  special  meaning  here,  and
              quotes   cannot   be   used   to  protect  arguments  containing

              The command name is relative to  the  Postfix  daemon  directory
              (pathname  is  controlled  by the daemon_directory configuration

              The command argument syntax for specific commands  is  specified
              in the respective daemon manual page.

              The  following command-line options have the same effect for all
              daemon programs:

              -D     Run the daemon under control  by  the  command  specified
                     with   the   debugger_command  variable  in  the
                     configuration file.  See DEBUG_README for hints and tips.

              -o name=value
                     Override  the  named configuration parameter. The
                     parameter value can refer to other  parameters  as  $name
                     etc.,  just like in  See postconf(5) for syntax.

                     NOTE 1: do not specify  whitespace  around  the  "=".  In
                     parameter values, either avoid whitespace altogether, use
                     commas instead of spaces, or consider overrides like  "-o
                     name=$override_parameter" with $override_parameter set in

                     NOTE 2: Over-zealous use of parameter overrides makes the
                     Postfix  configuration  hard  to understand and maintain.
                     At a certain point,  it  might  be  easier  to  configure
                     multiple  instances  of  Postfix,  instead of configuring
                     multiple personalities via

              -v     Increase the verbose logging level. Specify  multiple  -v
                     options  to  make  a  Postfix daemon process increasingly


       master(8), process manager
       postconf(5), configuration parameters


       Use "postconf readme_directory" or "postconf html_directory" to  locate
       this information.
       BASIC_CONFIGURATION_README, basic configuration
       DEBUG_README, Postfix debugging


       The Secure Mailer license must be distributed with this software.


       Initial version by
       Magnus Baeck
       Lund Institute of Technology

       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA