The Spam Filter is one of the main features in MDaemon's extensive suite of spam prevention tools. It incorporates heuristics to examine incoming email messages in order to compute a "score" based on a complex system of rules. The score is then used to determine the likelihood of a message being spam, and certain actions can be taken based on that score you can refuse the message, flag it as possible spam, and so on.
Addresses can be white or black listed, or designated as completely exempt from Spam Filter examination. You can have a spam report inserted into messages, showing their spam scores and how those scores were achieved, or you can generate the report as a separate email and have the original spam message included with it as an attachment. Further, you can even use Bayesian learning to help the Spam Filter learn to identify spam more accurately over time, thus increasing its reliability.
Finally, by examining many thousands of known spam messages, the rules have been optimized over time and are very reliable in detecting the fingerprint of a spam message. You can, however, customize or add new rules by editing the Spam Filter's configuration files to meet your specific needs.
MDaemon's Spam Filter uses an integrated, popular open-source heuristic technology. The homepage for the open-source project is: