Messaging Server supports the use of SpamAssassin, a freeware mail filter used to identify spam. SpamAssassin consists of a library written in Perl and a set of applications and utilities that can be used to integrate SpamAssassin into messaging systems.
SpamAssassin calculates a score for every message by performing a series of tests on the message header and body information. Each test succeeds or fails, and a verdict of true (spam) or false (not spam) is rendered. Scores are real numbers that can be positive or negative. Scores that exceed a specified threshold, typically 5.0, are considered to be spam. An example of a SpamAssassin result string is:
True ; 18.3 / 5.0
True indicates the message is spam. 18.3 is the SpamAssassin score. 5.0 is the threshold.
SpamAssassin is highly configurable. Tests may be added or removed at any time, and the scores of existing tests can be adjusted. This is all done through various configuration files. Further information on SpamAssassin can be found on the SpamAssassin web site.
The same mechanism used for calling out to the Brightmail spam and virus scanning library can be used to connect to the SpamAssassin spamd server. The module provided in Messaging Server is called libspamass.so.