An additional problem - now I'm getting emails from last September

First it was the problem (still unresolved) where my outgoing emails duplicate themselves and send multiple times. Now this morning I received an email I had already received - last September! I know it wasn’t still on the server so where did that come from?

I’m getting really frustrated. Do I have to use another email program?

Does the problem persist? If so, please send me your IMAP/POP log please but I am afraid it is a server side issue.