Sendmail Installation and Operation Guide

This document, the "ULTRIX-32 Programmer's Manual: Sendmail Installation and Operation Guide," published by Digital Equipment Corporation in May 1984, provides comprehensive instructions for installing, configuring, and managing the Sendmail internetwork mail routing facility on the ULTRIX-32 UNIX operating system.

Authored by Eric Allman, the manual describes Sendmail as a "crossbar switch" for relaying messages between different domains, handling message routing and limited header editing based on a complex configuration file.

Key areas covered include:

• Installation: Detailed steps for setting up Sendmail, including using pre-built configuration files (e.g., for Arpanet TCP or UUCP), and manually installing necessary binaries, configuration files (/usr/lib/sendmail.cf), mail queue directories (/usr/spool/mqueue), and alias databases (/usr/lib/aliases). It also covers configuring the system to start the Sendmail daemon on reboot.
• Normal Operations: Guidance on day-to-day maintenance, such as using "frozen" configuration files for quick startup, monitoring with the system log (syslog), managing and forcing the mail queue (including explanations of queue file formats), handling alias databases and per-user forwarding (.forward files), and understanding special header line interpretations.
• Arguments & Tuning: Explanation of various command-line flags for controlling Sendmail's behavior (e.g., setting queue intervals, debugging levels, specifying configuration files, and overriding options). It details how to tune Sendmail through timeouts, delivery modes, log levels, and file permissions, including security considerations.
• Configuration File: An in-depth section on the structure and semantics of the Sendmail configuration file, including rewriting rules, macro definitions, class definitions, mailer definitions, header definitions, and precedence, detailing the interaction of the five core rewriting rule sets.
• Appendices: Provide exhaustive lists and descriptions of command-line flags, configuration options, mailer flags, other compilation configurations, and a summary of all relevant support files created and used by Sendmail.

The manual is intended for system administrators and programmers responsible for deploying and maintaining a robust mail system in a UNIX environment.