Like many things in the Unix, GNU, and BSD worlds, the Postfix mail transport agent (MTA) is powerful but difficult to configure optimally. With basic instructions and a couple of hours (or more) to test the configuration, you can probably make Postfix work, but how do you make it work to its full potential? How do you make it more secure? How do you make it get rid of spam? How do you configure it for complex situations that involve multiple servers, email addresses, email groups, and domains? That's what "The Book of Postfix" is for.
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