Explosion in a Punctuation Factory - Excellent tutorial on how sendmail's rewriting rules work. Written by Brian Costales, the author of the best sendmail book around, "Sendmail", published by O'Reilly and Associates.
Jeremy Mates’s sendmail pages - Sendmail flow diagram with explanations and example configuration files for various situations.
Linux-Sec.net - Features minimum mail server hardening recommendations. Includes information on how to do it, antispam, filtering, open relay, antivirus, and statistics analyzer.
MeTA1 - MeTA1 is a successor of Sendmail X. Release notes, documentation, source code and contact information.
Sendmail FAQ - Frequently asked questions about sendmail.
Sendmail Inc. - Commercial Sendmail products and services.
Sendmail Routing with LDAP - Step-by-step instructions on using sendmail's LDAP routing feature. [Sun support contract required]
Sendmail: Theory and Practice - Homepage for the sedmail book by Paul A. Vixie and Frederick M. Avolio. Errata, sample chapter and ordering information.
- The open-source version of the most popular SMTP server. Downloads and documentation.
