Learning Red Hat Linux, Second Edition

Configuring a Mail Server

Does your ISP prohibit email message attachments larger than 10 MB or impose other restrictions that you find cumbersome? Your Linux system can provide an email server that isn’t subject to such arbitrary restrictions.

Tip

Mail is one of the services that ISPs are least likely to tolerate, owing to the ongoing war against spam. Often, ISPs block the ports used by sendmail so customers cannot operate unauthorized mail servers. Check with your ISP before taking the time to set up a mail server.

The sendmail package is a powerful Mail Transfer Agent (MTA), which transfers email from one system to another.

Tip

Don’t confuse sendmail and other MTAs with mail clients (sometimes called mail user agents), such as pine or mutt, which merely allow you to send and receive email. Mail clients communicate with MTAs, not with one another.

Depending on the options you selected during system installation, sendmail may already reside on your system. To check whether it’s installed, issue the command:

            rpm -q sendmail

If sendmail is installed, the command reports its version number; otherwise, the command reports that sendmail is not installed.

To install sendmail, use GnoRPM to install the sendmail, sendmail-cf, and m4 packages.

sendmailstarts automatically when you install it; to check the status of sendmail, issue the following command:

            service sendmail status

The command should identify the process ID of sendmail. If sendmail is not running, you can start it by ...