Red Hat Sendmail HOWTO

Red Hat, Inc.

This document is a HOWTO for sendmail on Red Hat Linux. It documents background information and many of the common problems associated with running sendmail on Red Hat Linux, and also discusses fixes and associated issues. The document assumes you are running sendmail on Red Hat Linux release 6.1 (Cartman) but should be fully compliant with Red Hat Linux 6.2 (Zoot) as well. The current sendmail version as of this release is sendmail 8.9.3 installed via RPm. One of the key features we are trying to accomplish with this document is to take all of the sting out of configuring sendmail. We will begin with some essential background and configuration information and then move on to more advanced topics.

Table of Contents
1. Introduction
1.1 Terminology
1.2 History
1.3 Forks & Other Sendmail Code Improvements
1.4 About sendmail on Red Hat Linux
1.5 Red Hat Enhancements
1.6 Other suggested enhancements
2. Installing & Configuring sendmail
2.1 What should be installed?
2.2 Where is everything?
2.2.1 sendmail-8.9.3-15.i386.rpm
2.2.2 sendmail-cf-8.9.3-15.i386.rpm
2.2.3 sendmail-doc-8.9.3-15.i386.rpm
2.2.4 File Location Review
3. What about working with sources?
3.1 Installing the Source RPM
3.2 Installing patches using spec files
3.3 Building the RPM
3.4 Now What?
3.5 What's next?
4. Beyond Default
4.1 The Home User
4.1.1 The Stand Alone Config
4.1.2 Masquerading, relaying and a word about UCE
4.1.3 So how do we configure this so it will work?
4.1.4 Fetching the mail?
4.1.5 Reading the mail
4.1.6 A couple of tweaks to make it all nice:
4.1.7 The Networked Home User Environment
4.2 The Corporate Environment
4.2.1 Sendmail on the Firewall
4.2.2 Using/not using DNS and MX Records with firewalls
4.2.2 Sendmail and Microsoft Exchange
4.3 The ISP Environment
4.3.1 The primary MX host (
4.3.2 The POP3 host (
4.3.3 The outbound SMTP host (
4.3.4 Summary for the three configurations
5. Command Switches, Debugging, and References
5.1 Switches
5.2 Debugging
5.3 References
5.3.1 Published
5.3.2 Online
6. Conclusion