MDaemon’s built-in spam filter includes a feature known as Bayesian Learning. Bayesian Learning allows MDaemon to “learn” what types of messages are spam and what types are not spam. This allows the spam filter to become more accurate over time.
It is important for users to properly train the Bayes system so that messages are correctly flagged as spam or non-spam. We do not recommend blacklisting the sender of spam messages because this does not help the Bayes engine learn from the message, and thus, has no effect on reducing spam. The easiest way to train the Bayes engine is for users to use the thumbs-up and thumbs-down icons in WorldClient (MDaemon’s webmail client) to feed the Bayes engine samples of spam and non-spam. The more spam and non-spam samples you feed to the Bayes engine, the more accurate the spam filter will become over time, thus, it is very important for users to use the thumbs-down icon on every spam message – whether it arrives in your Inbox or in your Junk Email folder. Likewise, for every false-positive (legitimate, non-spam message that is flagged as spam), you can use the thumbs-up icon to flag the message as non-spam.
This knowledge base article provides a more thorough explanation of Bayesian Learning and how to train the Bayesian Learning engine.
This video explains further.
If you are an end user and you do not see the thumbs-up and thumbs-down icons in WorldClient, the MDaemon administrator can take steps outlined in this video and blog post to make those icons appear.