Some of the popular MTAs in use are Sendmail, Exim, and Postfix.
Fedora and Red Hat Linux distributions by default ship with Sendmail as their MTA. However, switching to another MTA such as Exim or Postfix is quite easy.
Switch between MTAs
Method 1 : alternatives command
In Fedora or Red Hat, you can change the default MTA by using the
alternatives, an executable with a generic name on the file system is used to access a particular service. This executable is really a symbolic link to another symlink in the
/etc/alternatives/directory. For example, the
/usr/bin/sendmailis actually a symbolic link to
/etc/alternatives/mta. In order to select between Sendmail or Postfix, we just change the symlink for the
/etc/alternatives/mta. This is normally done with the
alternativescommand. Here are some examples:
To display which MTA alternative is in use:
# alternatives --display mta
To choose from the available MTA
alternativesfrom the command line :
# alternatives --config mta
To setup Postfix as the default mail system:
# alternatives --set mta
Method 2 : system-switch-mail
Another method of changing your default MTA in Fedora is to use the
/usr/sbin/system-switch-mail-noxtool. You will first have to install the
system-switch-mailpackage using Yum as follows.
$ su -c 'yum install system-switch-mail'
Once you have installed the
system-switch-mailpackage, you can run one of the corresponding tools to switch between the different MTAs installed in your system. When you run the system-switch-mail[-nox] command, you will see a self-explanatory selection dialog that allows you to switch to another MTA installed in your system.
Verify that the MTA is running
To verify that the MTA of your choice has started running, open
system-config-servicesin Fedora and see if it lists your MTA in the services that are running on your system.