Exim is an MTA developed by Philip Hazel at the University of Cambridge. Exim is designed for Internet mail hosts and provides flexibility, performance, and strong access controls. It has become a popular replacement for sendmail because it provides a compatible command-line interface.
This chapter explains how to integrate SpamAssassin into an Exim-based mail server to perform spam-checking for local recipients or to create a spam-checking mail gateway.
Exim is a complex
piece of software and, more than most MTAs, has an extensive and
complicated set of configuration options. This chapter assumes that
you are running Exim 4 and does not cover how to securely install,
configure, or operate Exim itself. For that information, see the Exim
documentation, the web site
http://www.exim.org, and the book
The Exim SMTP Mail Server: Official Guide for Release 4
by Philip Hazel (UIT Cambridge).
Exim consists primarily of a
single setuid executable,
exim, that performs different functions depending
on its command-line arguments. These functions include listening on
the SMTP port and receiving and enqueuing incoming messages, adding
locally generated messages to the queue, and processing the queue to
transmit outgoing messages. When compiled from source code,
exim is installed in
/usr/exim/bin, and the examples in this chapter
assume that directory is used.
Exim’s configuration file defaults to /usr/exim/configure. The configuration ...