IN THIS CHAPTER
Internet e-mail's inner workings
Understanding mail server software
Preparing your system
Installing and configuring the mail server software
Testing and troubleshooting
Configuring mail clients
Securing communications with SSL/TLS
Electronic mail hardly requires an introduction. Communications made through the original forms of e-mail helped shape the Internet. Widespread availability of access to e-mail and enhancements such as MIME (Multipurpose Internet Mail Extensions, which allow for inclusion of attachments and alternate message formats) have helped to make e-mail the most popular application on the Internet.
With a Linux system and a suitable Internet connection, you can easily set up your own mail server for personal or business use. This chapter includes a description of how Internet mail works at the protocol level, and then guides you through the process of setting up a mail server, complete with spam and virus filtering. In the final section, you learn how to secure network communications between clients and your mail server through the use of SSL/TLS (Secure Sockets Layer and Transport Layer Security) protocols.
The examples in this chapter are based on an Ubuntu system. (See Chapter 19 for more information about Ubuntu.) However, much of the knowledge you gain from setting up a mail server in Ubuntu applies to other Linux systems as well.
E-mail messages are generated either by an automated process, ...