Secrets in This Chapter
Understanding Mail Software
Learning the sendmail Configuration File
Using the m4 Macro Processor
Learning the sendmail.cf File Syntax
Exploring Other sendmail Files
Preparing the Access Database
Using the .forward File
Electronic mail (email) is the mainstay of the Internet. Email enables you to exchange messages and documents with anyone on the Internet. One of the most common ways people use the Internet is to keep in touch with friends, acquaintances, loved ones, and strangers through email. You can send a message to a friend thousands of miles away and get a reply within a couple of minutes. Essentially, you can send messages anywhere in the world from an Internet host, and that message typically makes its way to its destination within minutes-something you cannot do with paper mail, which is why paper mail is also called snail mail.
Because email can be stored and forwarded, you can arrange to send and receive email without making your Linux system a full-time host on the Internet. You won't get the benefits of nearly immediate delivery of messages, however, if your system is not an Internet host.
This chapter introduces you to the sendmail mail server for transferring mail. You learn about its configuration files and how to use its features to create mailing lists.