Configuring postfix

Authors:Michael JasonSmith; Fabien Hespul
Contact:Michael JasonSmith <>
Copyright:This document is licensed under a Creative Commons Attribution-Share Alike 4.0 International License by


Postfix provides the email interface for GroupServer. GroupServer uses Postfix to queue email that is delivered to groups, and pass the email messages to GroupServer.

Configuration files for Postfix that are specific to GroupServer are created when GroupServer is installed. However, it is necessary to change the main Postfix configuration files for the system so Postfix will send email messages on to GroupServer. The Postfix configuration will achieve the following.

  • Each group will have a unique email address.
  • The Postfix configuration will work, untouched, for any and all groups once it has been set up.
  • A single virtual address will respond to all emails coming in to any possible group on your site.
  • When an email comes in for any group on a it is passed on to GroupServer, which then adds the message to the correct group.

There are two configuration files, created by GroupServer during installation, that will provide what we want once they have been integrated into the existing Postfix configuration. Both are found in the postfix_config directory after GroupServer has been built.

This file maps all email messages that are sent to any of your GroupServer groups to the single groupserver-automagic@localhost email-address. See virtual(5) for more information.
This file maps the groupserver-automagic address to a command: piping the email to the smtp2gs script. See aliases(5) for more information.

See also

The Ubuntu Community Postfix Documentation is useful if you are new to administering Postfix.

Postfix configuration

Below are the steps for configuring Postfix for either Debian or Ubuntu.


You will need to be the root user to carry out most of these tasks. Commands that need to be run as root will be shown with # prompt, rather than a $.

  1. Copy the configuration files from the GroupServer installation into the Postfix configuration directory.

    # cp postfix_config/groupserver.* /etc/postfix
  2. Change the ownership of the files to root:

    # chown root.nogroup /etc/postfix/groupserver.*

    If you are on a system other than Ubuntu you will need to ensure that the files are owned by the Postfix user. Running the following will display the user-name of the Postfix user.

    $ /usr/sbin/postconf | grep default_privs | cut -f3 -d" "
  3. Open the file /etc/postfix/ in a text editor.

  4. Update the aliases.

    1. Find the line that begins with alias_maps.

    2. Add the item hash:/etc/postfix/groupserver.aliases to the end of the alias_maps line. Use a comma to separate the new item from any existing items. For example

      alias_maps = hash:/etc/aliases,hash:/etc/postfix/groupserver.aliases
    3. Find the line that begins with alias_database.

    4. Add the item hash:/etc/postfix/groupserver.aliases to the end of the alias_database line. Use a comma to separate the new item from any existing items. For example

      alias_database = hash:/etc/aliases,hash:/etc/postfix/groupserver.aliases
  5. Update the virtual alias.

    1. Find the line that begins with virtual_alias_maps. If no line exists add one after the alias_database line.

    2. Add the item hash:/etc/postfix/groupserver.virtual to the end of the virtual_alias_maps line. For example

      virtual_alias_maps = hash:/etc/postfix/groupserver.virtual
  6. Add the following to the bottom of the file, unless it is previously defined

    smtpd_authorized_verp_clients =,localhost
  7. Generate the Postfix hashes by running postmap and postalias:

    # postmap /etc/postfix/groupserver.virtual
    # postalias /etc/postfix/groupserver.aliases
  8. Restart Postfix using service:

    # service postfix restart

See also

More information about the GroupServer smtp2gs command — including optional arguments, return values, and examples — is available from the smtp2gs documentation.