In the last week or so Thunderbird 141 leaves POP3 messages on server, even though Leave Messages on Server is unchecked in Server Settings. As the messages are left on my ISP server, they get repeatedly downloaded into TB resulting in several multiples of the same message. I subsequently installed Remove Duplicates Add-On, but that only temporarilty cleans up the mess. I have several times compacted folders, but no improvement. I even unselected Automatically Download New Messages in Server Settings and the other two choices under Leave Messages on Server, but no joy -- multiple messages are only slowed down. The only unsatisfactory way to stop all this is for me to manually delete messages from my ISP webmail client after I see they are downloaded into TB. Everything in TB was working perfectly until recently. My ISP is unaware of any recent changes to settings on their end. TB is installed on a fully updated Windows10 Pro 64 bit PC. I have tried all suggestions found online and in Mozilla Support over the years, which haven't worked. Please advise if there is something I have missed OR there is a fix to this now or upcoming. Thanks.