The only "odd" items in your list are the highlighted Inbox and its associated Drafts, Sent and Trash folders. I suspect these are clones of the "proper" Inbox, given that the number of unread messages are identical. I have heard of cases where copied folders remain attached to their original location, and you appear to have something like this going on here. Do you recall ever trying to move, copy or drag whole folders from one place to another? I always advise against this when it arises in discussions. I don't know what is supposed to happen when a folder is dragged from one account to another, particularly when one of them is in an IMAP-connected account. A folder in an IMAP-connected account is linked to a folder on the server. I have no idea what is supposed to happen if such a folder is moved. What should be done with the connection to the server? In your place I'd try to remove the highlighted folder and its siblings, but I'd half expect the original folder to go too, so I'd make a copy of my profile first. I'd also look at removing the problematic Inbox and its siblings by removing their data files from the profile, but I fear the real scrambling is in the settings file, and the problem folders may well just re-appear. I don't know for sure if this is part of the trouble you're having with filters, but having two folders with the same name in Local Folders seems a recipe for trouble. A new clean profile would almost certainly clear things up, but there would be a significant amount of work in setting up accounts again, and rescuing all your messages stored under Local Folders. Info on the profile: https://support.mozilla.org/en-US/kb/profiles-tb