Symptoms

• Increase in spam after Plesk upgrade
• psa-spamassassin installed and service is running
• extended mail headers don’t have any reference to spam scores

Others have reported that it works for some mailboxes and not others. Also issues surrounding ignoring white/black lists

Tested Scenario

• Upgrade from 9.01 -> 9.54

Fixes

• In the control panel: Server -> Spam filter Settings -> uncheck “Apply individual settings to spam filtering”
• Save
• Send a test email and see if the spam scores are now in the extended headers

I didn’t come across this fix when attempting to find a solution but it seams to work.

This is a known bug (apparently). Many seem to try upgrading to v10 to solve, but others have reported that it was this upgrade that has resulted in the problem occuring.