LPI Linux Certification in a Nutshell, 2nd Edition

Objective 2: Operate and Perform Basic Configuration of Mail Transfer Agent (MTA)

The Sendmail MTA is responsible for handling a large portion of email sent on the Internet and inside enterprises. It has broad capabilities to handle mail routing and can perform complex rewriting of email addresses. Unfortunately, sendmail's configuration file can also appear to be somewhat cryptic to administrators, and detailed configuration of sendmail has become known as somewhat of an art.

Configuration details of sendmail are nontrivial and beyond the scope of the LPIC Level 1 Exams but is covered in depth at Level 2. However, a basic sendmail configuration for a system in an established domain is relatively simple to implement and is covered in Exam 102.

Configuring sendmail

The sendmail configuration file is /etc/sendmail.cf. (Be aware that on some systems some or all of sendmail's configuration files could be in an alternate location, such as /etc/mail.) This text file contains information to control the processing of mail on your system, and it is read at every invocation of sendmail. Each line in the file defines a configuration command, which begins with a short one- or two-letter command definition. The file can also contain comments beginning with #. To simplify a basic setup, example sendmail.cf files exist in most installations.

The smart host parameter

To enable mail transfer inside an established organization, you may need to configure sendmail to transfer messages to a smart host ...