MASTER(5)                                                            MASTER(5)

       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  con-
       figuration file defines how a client program connects to a service, and
       what daemon program runs when a service is requested.  Most daemon pro-
       cesses  are short-lived and terminate voluntarily after serving max_use
       clients, or after inactivity for max_idle or more units of time.

       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:

       o      Empty lines and whitespace-only lines are ignored, as are  lines
              whose first non-whitespace character is a `#'.

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

       o      Each logical line defines a single Postfix service.   Each  ser-
              vice  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.

       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 (see
                     hosts(5) or services(5)) or in numeric form  (IP  address
                     or port number).  Host information may be enclosed inside
                     "[]"; this form is necessary only with IPv6 addresses.

                     Examples: a  service  named  or  ::1:smtp
                     receives mail via the loopback interface only; and a ser-
                     vice 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 stream 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 8 and earlier systems the unix type is  imple-
                     mented with streams sockets.

                     The  service listens on a UNIX-domain datagram 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

              fifo (obsolete)
                     The service listens on a FIFO (named pipe) and is  acces-
                     sible 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 stream socket, and
                     is accessible to local clients only. It receives one open
                     connection   (file  descriptor  passing)  per  connection

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

                     On Solaris 8 and earlier systems the pass type is  imple-
                     mented with streams sockets.

                     This feature is available as of Postfix version 2.5.

       Private (default: y)
              Whether  or not access is restricted to the mail system.  Inter-
              net (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: Postfix >= 3.0: n, Postfix <3.0: y)
              Whether  or  not  the  service  runs  chrooted to the mail queue
              directory (pathname is controlled by the queue_directory config-
              uration 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 Post-
              fix  source show how to 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 num-
              ber 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 auto-
              matic 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  sin-
              gle-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 white-
              space. To protect whitespace,  use  "{"  and  "}"  as  described

              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 config-
                     uration file.  See DEBUG_README for hints and tips.

              -o { name = value } (long form, Postfix >= 3.0)

              -o name=value (short form)
                     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: With the  "long  form"  shown  above,  whitespace
                     after  "{",  around  "=",  and before "}" is ignored, and
                     whitespace within the parameter value is preserved.

                     NOTE 2: with the "short form" shown above, do not specify
                     whitespace  around  the  "="  or  in parameter values. To
                     specify a parameter value that contains  whitespace,  use
                     the  long  form described above, or use commas instead of
                     spaces, or specify the value in Example:

                         submission inet .... smtpd
                             -o smtpd_xxx_yyy=$submission_xxx_yyy

                         submission_xxx_yyy = text with whitespace...

                     NOTE 3: 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  mul-
                     tiple instances of Postfix, instead of configuring multi-
                     ple personalities via

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

              Other command-line arguments
                     Specify "{" and "}" around command arguments that contain
                     whitespace  (Postfix 3.0 and later). Whitespace after "{"
                     and before "}" is ignored.

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

       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

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA