Introducing Postfix


Sendmail has been the de facto MTA of choice for the Internet for a long time. At one point, it was the power behind 90% of the email traffic across the world, although it has now become largely superseded by worthier programs.

One of the more popular programs that have become available is Postfix, which was developed and is exclusively maintained by Wietse Venema. Designed to be a drop-in replacement for Sendmail, Postfix allows the system administrator to literally replace Sendmail without any detriment to the system.

Postfix was designed from the ground up to retain compatibility with Sendmail but to work in a more efficient fashion. Sendmail is notoriously system intensive when handling either large volumes of mail or large numbers of clients. One command pretty much handles everything, making Sendmail something of a monolith. On the other hand, Postfix works with several individual modules all working together, using modules only when needed.

Making the Switch

Postfix is easy to install and configure. The first thing to do is to make a backup of all your Sendmail information that you want to keep just in case. After you have done this, you need to use yum to remove Sendmail and install Postfix.

After Postfix has been successfully installed, you can begin configuring it. The scripts for Postfix are all located in /etc/postfix and include

  • install.cf The script generated when Postfix is installed. This file lists the locations Postfix uses and can be a big help when working with the main.cf file.

  • main.cf The principal configuration script for Postfix. Within the remarks at the start of the script, you are advised to change only a couple of options at any time. This is sage advice, given that there are more than 300 possibilities!

  • master.cf The throttle control for Postfix. This script allows you to change settings for Postfix that directly affect the speed at which it works. Unless you have a reason to tinker with this file, leave it alone. Trust me: You will know when you need to make changes.

  • postfix-script The script used by Postfix as a wrapper. You cannot execute it directly; instead it is called by Postfix itself.

You can keep your original Sendmail aliases file for use with Postfix because it will not make much difference to it.

You will also require the services of system-switch-mail, which can also be installed by using yum.

After system-switch-mail has been successfully installed, switch to a root terminal and type the following:

# system-switch-mail


You are then greeted with a simple text screen asking which MTA you want to use. Select Postfix and simply press Enter. After a few seconds, a new window appears informing you that your MTA has been successfully switched. All you then need to do is ensure that Postfix is enabled in runlevel 5 by checking the service (system-config-services).

Further configuration of Postfix focuses on the main.cf file, which is extensively documented throughout the file using comments.

The beauty of Postfix is that it can be used in any situation from a single home user to a large corporation that has thousands of clients, even up to the ISP level. It can even be linked to MySQL for authentication purposes and virtual hosting.



Red Hat Fedora 5 Unleashed
Red Hat Fedora 5 Unleashed
ISBN: 067232847X
EAN: 2147483647
Year: 2004
Pages: 362

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