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# 5.5 Electronic Mail

Like most UNIX systems, Linux provides a number of software packages for using electronic mail. E-mail on your system can either be local (that is, you only mail other users on your system), or networked (that is, you mail, using either TCP/IP or UUCP, users on other machines on a network). E-mail software usually consists of two parts: a mailer and a transport. The mailer is the user-level software which is used to actually compose and read e-mail messages. Popular mailers include `elm` and `mailx`. The transport is the low-level software which actually takes care of delivering the mail, either locally or remotely. The user never sees the transport software; they only interact with the mailer. However, as the system administrator, it is important to understand the concepts behind the transport software and how to configure it.

The most popular transport software for Linux is `Smail`. This software is easy to configure, and is able to send both local and remote TCP/IP and UUCP e-mail. The more powerful `sendmail` transport is used on most UNIX systems, however, because of its complicated setup mechanism, many Linux systems don't use it.

The Linux Mail HOWTO gives more information on the available mail software for Linux and how to configure it on your system. If you plan to send mail remotely, you'll need to understand either TCP/IP or UUCP, depending on how your machine is networked (see Sections 5.3 and 5.4). The UUCP and TCP/IP documents listed in Appendix A should be of help there.

Most of the Linux mail software can be retrieved via anonymous FTP from `sunsite.unc.edu` in the directory `/pub/Linux/system/Mail`.

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