Overview

"You are in a maze of twisty little Sendmail rules, all obscure."

We culled the above quote from Mike Shaddock's Usenet signature, and we believe that it is the best possible explication of that "sinking feeling" folks get when they get lost in the labyrinthine depths of a sendmail.cf file.

We are about to take a (nearly) line-by-line stroll through a sendmail.cf file, in which groups of lines are presented with commentary separating them. This is basically the file we use on our mail hosts. Later we will discuss how to build and maintain sendmail.cf files, but for now, remembering what we covered in the previous chapters, let's get to it.

A double espresso would be good right about now.

8.1. The Sendmail Configuration Files

In looking at the configuration file, you will learn how it works and how to modify (or even write!) one yourself. To review, let's remember that a configuration file has comments, macro definitions, class definitions, configuration options, header definitions, rulesets made up of rules, and mailer definitions. Our sendmail.cf is set up so that everything is presented, mostly, in that order (we put mailer-specific rulesets with the mailer definitions).

8.2. Opening Comments

A sendmail.cf file usually has some historical comments at the top. For brevity, we have taken them out of our examination in this chapter. The configuration file in its entirety is presented in Appendix ?.

8.3. Macros and Classes

We define P to be a...