Configuring a Smart Host on Postfix to pass mail through Email Security for Outbound
Postfix is an MTA for routing and the deliveries of emails. Similar to Microsoft Exchange and Lotus Notes but on a Linux platform.
To set the smarthost for Postfix to relay mail to the Email Security for outbound, edit the main.cf configuration file under the Postfix directory. Usually [ etc/postfix/main.cf ].
Open main.cf with your favorite text editor and look for a line called: relayhost=
Put in the IP of the Email Security server between square brackets like the example above. If relayhost= does not exist in the configuration file, type it in manually.
Now reload postfix by typing postfix reload from the command prompt on the Postfix server.
**Additional information that is not required below for setting up a smarthost on Postfix**
You can also setup a fallback smarthost from the main.cf file. Say that you have two Email Security servers and you want it to fallback to the second server if the primary goes down. An example is a Split Configuration with the Email Security with two Remote Analyzers.
Open up main.cf with your favorite text editor and search for an entry or create one called: smtp_fallback_relay=
Put in the IP of the second Email Security server between square brackets like the example shown above.