Erle Robotics Introduction to Networking in Linux


Electronic mail transport has been one of the most prominent uses of networking since the first networks were devised.


Sendmail is the standard mail server program or Mail Transport Agent for UNIX platforms. It is robust, scalable, and when properly configured with appropriate hardware, handles thousands of users without blinking. More information about how to configure Sendmail is included with the sendmail and sendmail-cf packages.For more information use man sendmail and man aliases.

Qmail is another mail server, gaining popularity because it claims to be more secure than Sendmail. While Sendmail is a monolithic program, Qmail consists of smaller interacting program parts that can be better secured. Postfix is another mail server which is gaining popularity.

These servers handle mailing lists, filtering, virus scanning and much more. Free and commercial scanners are available for use with Linux. Examples of mailing list software are Mailman, Listserv, Majordomo and EZmlm. See the web page of your favorite virus scanner for information on Linux client and server support. Amavis and Spamassassin are free implementations of a virus scanner and a spam scanner.

Remote mail servers

The most popular protocols to access mail remotely are POP3 and IMAP4. IMAP and POP both allow offline operation, remote access to new mail and they both rely on an SMTP server to send mail.

While POP is a simple protocol, easy to implement and supported by almost any mail client, IMAP is to be preferred because:

  • It can manipulate persistent message status flags.

  • It can store as well as fetch mail messages.

  • It can access and manage multiple mailboxes.

  • It supports concurrent updates and shared mailboxes.

  • It is also suitable for accessing Usenet messages and other documents.

IMAP works both on-line and off-line.

it is optimized for on-line performance, especially over low-speed links.

Mail user-agents

There are plenty of both text and graphical E-mail clients, we'll just name a few of the common ones. Pick your favorite.

The UNIX mail command has been around for years, even before networking existed. It is a simple interface to send messages and small files to other users, who can then save the message, redirect it, reply to it etcetera.

While it is not commonly used as a client anymore, the mail program is still useful, for example to mail the output of a command to somebody.

  • Sending mail:
mail [email protected] < doc.txt
mail -s “Hello Erle” [email protected]
echo “This will go into the body of the mail.” | mail -s “Hello Erle” [email protected]
  • Reading Mail:

In normal usage mail is given no arguments and checks your mail out of the post office, then prints out a one line header of each message found.The current message is initially the first message (numbered 1) and can be printed using the `print command (which can be abbreviated p). You can move among the messages much as you move between lines in ed(1), with thecommands + and - moving backwards and forwards, and simple numbers.

For those users who prefer a graphical interface to their mail (and a tennis elbow or a mouse arm), there are hundreds of options. The most popular for new users are Mozilla Mail/Thunderbird, which has easy anti-spam configuring options, and Evolution, the MS Outlook clone. Kmail is popular among KDE users.

For more info and mail installation/configuration, you can visit: