MASTER(5) File Formats Manual 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 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 run the server under control by inetd(8) or equivalent.

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



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



Each logical line consists of eight fields separated by
    whitespace. These are described below 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.



  

  
The service name syntax depends on the service type as described
    next.

  

  
Specify one of the following service types:







  

  
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 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 = loopback-only" in main.cf, instead
        of hard-coding loopback IP address information in master.cf or in
        main.cf.

  

  

  
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 main.cf).

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

  

  

  
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 main.cf).

  

  

  
The service listens on a UNIX-domain 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 (pathname 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.

  







  

  
Whether or not access is restricted to the mail system. Internet (type
      inet) services can't be private.

  

  
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.

  

  

  
Whether or not the service runs chrooted to the mail queue directory
      (pathname is controlled 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) 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.

  

  

  
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.

  

  

  
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.

  

  

  
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 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 daemon manual page.

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

  







  

  
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.

  

  

  

  
Override the named main.cf configuration parameter. The parameter value
      can refer 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 whitespace, 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 personalities via master.cf.

  

  

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

  

  
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










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
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