Configuring Postfix

Postfix is an alternative to sendmail that ships with most major Linux distributions, although many of them don’t install it by default. If your distribution doesn’t ship with Postfix but you want to try it, check the Postfix home page ( for source code download links. You might be able to install a binary package intended for another distribution, but chances are you’ll need to modify or replace the SysV startup scripts.

As with sendmail, configuring Postfix for your network requires understanding the main Postfix configuration files. You can then set the main Postfix options, including those relating to addressing, relaying, and spam control.


Postfix is a very complex server, so this chapter can present only the basics of its configuration. For more information, consult the documentation at the Postfix web site or a book on the subject, such as Postfix: The Definitive Guide (O’Reilly).

Postfix Configuration Files

Linux Postfix binary packages typically store configuration files in /etc/postfix. The main configuration file in this directory is , which controls the overall Postfix configuration. This file consists of comments, which are denoted by lines beginning with hash marks (#) and option lines of the form:

                  variable = value

The variable is typically a descriptive name, such as relayhost to set the hostname of another SMTP server that’s to act as a mail relay. The value can be a hostname, IP address, filename, or other string. ...

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