@Kim_E A little off this topic, but I wanted to mention, when you mark a user's posts as spam, you're teaching Spam Quarantine that those types of posts are spam, not normal posts. Since it learns as it goes, the more normal posts that are marked as spam, the more of a chance you'll start seeing other user's normal posts caught up in quarantine.
A better option after banning a user might be to just remove all their posts (using batch processing if available), or allowing their posts to remain in the community to keep from disrupting the flow of conversation.
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