Some services in Fedora Linux can be implemented by several different software packages. Although you can, you probably don’t want to run multiple mail and print servers on the same computer. At the very least, you should set the software you want to use by default.
In Fedora Linux, an “alternatives” feature is packaged into the operating system. Alternatives is an implementation of the Debian GNU/Linux alternatives feature. In essence, alternatives links the software you choose (or leave by default) into the common locations where the service being implemented is launched or made available.
See the “Choosing Software Alternatives” section in Chapter 10 for more information on the alternatives feature.
The first services to be implemented under alternatives in Fedora Linux are print and mail server packages. However, when the LPRng print service was dropped from Fedora, it left mail as the only service that's supported by the alternatives feature.
Assuming you have multiple mail MTAs installed, to switch your mail service from the main Red Hat menu, select System Tools ® Mail Transport Agent Switcher (or type system- switch-mail from a Terminal window). The window that appears enables you to choose between the Sendmail (default), Postfix, and Exim mail-transport agents.
Figure C-1 shows an example of the system-switch-mail window.
Figure C-1: Change your default mail-transport agent with system-switch-mail.