phpman > man > master(5)

MASTER(5)                                File Formats Manual                               MASTER(5)



NAME
       master - Postfix master process configuration file format

DESCRIPTION
       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,  started
       on-demand  by  the  master(8) process.  The master.cf 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 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 execute the software
       with inetd(8) or equivalent.

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

SYNTAX
       The general format of the master.cf file is as follows:

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

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

       •      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 master.cf  service
              definitions does not matter.

       Each  logical line consists of eight fields separated by whitespace.  These are described be‐
       low in the order as they appear in the master.cf file.

       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 next.

       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  en‐
                     closed inside "[]"; this form is necessary only with IPv6 addresses.

                     Examples:  a  service  named  127.0.0.1:smtp  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 parameter.


                     Note:  with  Postfix  version  2.2  and  later specify "inet_interfaces = loop‐‐
                     back-only" in main.cf, instead of hard-coding loopback IP  address  information
                     in master.cf or in main.cf.

              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  (path‐
                     name controlled with the queue_directory configuration parameter in main.cf).

                     On  Solaris  8  and  earlier  systems the unix type is implemented with streams
                     sockets.

              unix-dgram
                     The service listens on a UNIX-domain datagram socket and is accessible for  lo‐
                     cal clients only.

                     The  service  name is a pathname relative to the Postfix queue directory (path‐
                     name controlled with the queue_directory configuration parameter in main.cf).

              fifo (obsolete)
                     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 (path‐
                     name controlled with the queue_directory configuration parameter in main.cf).

              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 request.

                     The service name is a pathname relative to the Postfix queue  directory  (path‐
                     name controlled with the queue_directory configuration parameter in main.cf).

                     On  Solaris  8  and  earlier  systems the pass type is implemented 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.  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  main.cf
              file).

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

       Chroot (default: Postfix >= 3.0: n, Postfix <3.0: y)
              Whether or not the service runs chrooted to the mail queue directory (pathname is con‐
              trolled by the queue_directory configuration variable in the main.cf file).

              Chroot should not be used with the local(8), pipe(8), spawn(8),  and  virtual(8)  dae‐
              mons.   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 show how  to
              set up a Postfix chroot environment on a variety of systems. See also BASIC_CONFIGURA‐
              TION_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 timer.

       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  exam‐
              ple, 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 con‐
              taining whitespace. To protect whitespace, use "{" and "}" as described below.

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

              The  command argument syntax for specific commands is specified in the respective dae‐
              mon 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  main.cf  configuration file.  See DEBUG_README for hints and
                     tips.

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

              -o name=value (short form)
                     Override the named main.cf configuration parameter. The parameter value can re‐
                     fer  to  other parameters as $name etc., just like in main.cf.  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  white‐
                     space,  use  the long form described above, or use commas instead of spaces, or
                     specify the value in main.cf. Example:

                     /etc/postfix/master.cf:
                         submission inet .... smtpd
                             -o smtpd_xxx_yyy=$submission_xxx_yyy

                     /etc/postfix/main.cf
                         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 multiple instances of Postfix, instead of configuring  multiple  per‐
                     sonalities via master.cf.

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

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

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

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

LICENSE
       The Secure Mailer license must be distributed with this software.

AUTHOR(S)
       Initial version by
       Magnus Baeck
       Lund Institute of Technology
       Sweden

       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



                                                                                           MASTER(5)