Add the SpamAssassin Anti-SPAM management interface to your Plesk software. Activating this on your license adds an additional Spam filter to your system that is configurable Server-wide or at the domain level.
SpamAssassin is an open source mail filter to identify spam. Using its rule base, it uses a wide range of heuristic tests on mail headers and body text to identify ""SPAM"".SpamAssassin as a mail content filter. This tool is completely customizable by and for each user. These instructions tell you how to filter email, disable spamassasin, customize the tagging, and delete spam on the mail server.