A.1. Prerequisites

For these examples, you need the Exim Mail Transport Agent, preferrably with Tom Kistner's Exiscan-ACL patch applied. Prebuilt Exim+Exiscan-ACL packages exist for the most popular Linux distributions as well as FreeBSD; see the Exiscan-ACL home page for details[1].

The final implementation example at the end incorporates these additional tools:

Other optional software is used in examples throughout.



In particular, Exim is perhaps most popular among users of Debian GNU/Linux, as it is the default MTA in that distribution. If you use Debian ("Sarge" or later), you can obtain Exim+Exiscan-ACL by installing the exim4-daemon-heavy package:
# apt-get install exim4-daemon-heavy