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.
The final implementation example at the end incorporates these
additional tools:
SpamAssassin
- a popular spam filtering tool that analyzes mail content
against a large and highly sophisticated set of
heuristics.
greylistd
- a simple greylisting solution written by yours truly,
specifically with Exim in mind.
Other optional software is used in examples throughout.