The fourth part of this book provides a comprehensive reference for all the innerworkings of the configuration file, and for debugging and rule testing.

Chapter 27, The Configuration File

Presents an overview of the sendmail.cf file. Comments, joined lines, and the V configuration command are detailed.

Chapter 28, Rules

Shows how the workspace is rewritten by individual rules. Operators, like $*, are explained here.

Chapter 29, Rule Sets

Covers the flow of addresses through rule sets, and illustrates the special uses of rule sets 0 through 5, and the check_ rule sets.

Chapter 30, Delivery Agents

Shows how to define mail delivery agents with the M configuration command. The F= flags are also listed.

Chapter 31, Defined Macros

Shows how to define and use macros. An explanation of all macros currently in use is included.

Chapter 32, Class Macros

Shows how multiple values can be stored in class macros. The special uses of the $= and $~ prefixes are also shown.

Chapter 33, Database Macros

Shows how to create, declare, and use external databases and network maps.

Chapter 34, Options

Shows how to declare options from the command line and in the configuration file. Then every option is explained.

Chapter 35, Headers

Describes the legal contents and form of headers in email messages and in the H configuration command. Then many common headers are explained.

Chapter 36, The Command Line

Shows the many ways to run sendmail with emphasis on its numerous command-line switches.

Chapter 37, Debugging with -d

Documents the many debugging switches available with sendmail.

Chapter 38, Rule-Set Testing with -bt

Describes sendmail's rule-testing mode and shows the many ways to use that mode to solve problems.