What is also happening is that Thunderbird is creating new inboxes (Inbox-1, etc.). It's almost as if "deleting" a message causes these new mailboxes to appear. And each mailbox seems to duplicate the next. They are not all messages but instead a select number. If I manually move a message to the trash rather than using the "delete" button in the message pane, this does not happen. Compacting the folders does not cause this to happen. I do have two pop email accounts, and the new folder creation seems to happen only with the earthlink account. It does not happen with the non-earthlink account, but the disappearing list happens as well.