What do the SpamAssasin Spam Filter scores in Plesk mean?

Question

• What do the SpamAssasin Spam Filter scores in Plesk mean?
• Should I set a higher or lower score in the Plesk Spam Filter?
• Does a lower spam score in the Spam Filter block less or more spam?
• Does a higher spam score in the Spam Filter block more or less spam?

Answer

Score 1: Aggressive - will mark many legitimate emails as spam. (Many false positives)
Score 2: Mostly Aggressive - may mark a good portion of the legitimate emails as spam. (a medium amount of false positives)
Score 3: A bit Aggressive  - may mark a small amount of legitimate emails as spam. (a small amount of false positives)
Score 4: More strict Middle ground - recommended for well-tested servers that still let some spam pass through after using score 5
Score 5: Middle ground (Default setting, recommended as a starting point)
Score 6: Less strict Middle ground (a very small amount of false negatives)
Score 7: A bit Passive (a bigger amount of false negatives)
Score 8: Mostly Passive (an even bigger amount of false negatives is expected)
Score 9: Almost entirely Passive - All legitimate emails will arrive (many false negatives)
Score 10: Passive. This will catch only the most obvious spam (the most false negatives)

The general rules for deciding which score to use state that you should start with the usage of Score 5 (Default) and proceed as follows:

• Lower the score if you find Spam emails are still making it through the filter
• Raise your score if you find that emails from legitimate sources are filtered by mistake

Additional information

SpamAssassin Spam Filter | Plesk Obsidian documentation