I have had SpamSieve over a year. LOVE it! However I do a lot of website development, and I like to hide my mail when I’m not using it. Every good piece of mail that comes in, makes my Mail.app front most window. Could SpamSieve have anything to do with it?
I don’t think so. Does unchecking (temporarily) the SpamSieve rule in Mail’s preferences fix the problem? If the problem still occurs when SpamSieve is not active, it’s probably not related.
Do you have any rules in Mail’s preferences that run AppleScripts? Sometimes people have an unnecessary script rule that causes that.
Problem still not solved, but it does happen when I have spamSieve disabled… so it’s not this… Hope it clears up after my Catalina update… If I get this solved I will update you, just incase someone else has this similar problem.