If you find that Spamassassin is failing to tag incoming unsolicited commercial emails as SPAM, then it may be that your SPAM recognition threshold is set too high. Alternatively, if you find that a significant number of legitimate incoming email has been SPAM-tagged, you may wish to raise it.
Spamassassin uses a points system based on a set of rules to gauge the likelihood that an incoming email should be regarded as SPAM. To modify the number of points at which a particular email is considered to be SPAM, login to Plesk as admin. Go to the Server section, and select the Spam Filter option. The SPAM points threshold is labelled as "The score that a message must receive to qualify as spam". Update this value as required, and press the OK button.
Note that this applies to dedicated server / VDS accounts with Spamassassin installed, not the shared server AV / anti-SPAM service.
Spamassassin uses a points system based on a set of rules to gauge the likelihood that an incoming email should be regarded as SPAM. To modify the number of points at which a particular email is considered to be SPAM, login to Plesk as admin. Go to the Server section, and select the Spam Filter option. The SPAM points threshold is labelled as "The score that a message must receive to qualify as spam". Update this value as required, and press the OK button.
Note that this applies to dedicated server / VDS accounts with Spamassassin installed, not the shared server AV / anti-SPAM service.