Ouch. What I guess has happened is that when you connected to the new account, because it had the same account details (name and password) as your old one, Thunderbird overwrote everything in your existing profile with the content of the new account -- which, being empty, meant that all your previous info was erased. I assume also that you didn't have the old profile backed up. If you are a Windows user and have the 'restore' function activated, you may be able to use that to 'restore' your whole computer to a time before you activated the AOL account. If so, there's a chance that your old profile (with all its contents) could be recovered. You would need to: - disconnect your computer from the internet before attempting the restore so that there is no risk of new data being downloaded and corrupting the old data before you have recovered it; - if the restore is successful, copy your old Thunderbird profile to a safe storage medium (preferably external storage); - reconnect to the internet and set up your AOL account all over again; - then use an add-on like ImportExportTools to move the content from your old Verizon account into the new one. Bear in mind, of course, that the restore will revert everything on your computer to an earlier state, so you will risk losing any documents, photos, music files etc. that you have created since the restore point. You will need to back up all of them too before attempting the restore process.

Thanks for the help. I had looked at ImportExportTools yesterday, and saw that the import function will not bring folders into an IMAP account which is what I set up with AOL. My previous account was a POP account, so I think I'm just out of luck. I've managed to restore filters and folders, so hopefully the loss of email will simply tell me I was holding on to unnecessary stuff.