Linux Network Administrator's Guide, 3rd Edition

Chapter 12. sendmail

It’s been said that you aren’t a real Unix system administrator until you’ve edited a sendmail.cf file. It’s also been said that you’re crazy if you’ve attempted to do so twice.

Fortunately, you no longer need to directly edit the cryptic sendmail.cf file. The new versions of sendmail provide a configuration utility that creates the sendmail.cf file for you based on much simpler macro files. You do not need to understand the complex syntax of the sendmail.cf file. Instead, you use the macro language to identify the features you wish to include in your configuration and specify some of the parameters that determine how that feature operates. A traditional Unix utility, called m4, then takes your macro configuration data and mixes it with the data it reads from template files containing the actual sendmail.cf syntax to produce your sendmail.cf file.

sendmail is an incredibly powerful mail program that is difficult to master. Any program whose definitive reference (sendmail, by Bryan Costales with Eric Allman, published by O’Reilly) is 1,200 pages long scares most people off. And any program as complex as sendmail cannot be completely covered in a single chapter. This chapter introduces sendmail and describes how to install, configure, and test it, using a basic configuration for the Virtual Brewery as an example. If the information presented here helps make the task of configuring sendmail less daunting for you, we hope you’ll gain the confidence to tackle more ...