Hi Matt,

Rebooting hasn't helped, so I'll work through your suggestions now. Thanks.

I assume clean TBird installs are better?

I'm back with v52.9.1 and at present TBird appears to be recreating some of the Inbox contents. I'm leaving it to run & will apply your suggestions when it either finishes or fails.

Even if emails are restored, I may use that extension in the hope of avoiding any repeat of the problem. I'll report back once I know the outcome of what's currently happening.

Hi Matt,

I've followed all the steps you outlined but my email is just a big mess.

No email displays in my Inbox and the other folders are all wrong. Emails are just randomly filed in folders and aren't where they should be.

Also my folders indicate the number of emails they contain, but the number of emails actually in the folder is totally different.

I have no idea how much of my email is not displaying. Is there anything else I can try?

I'm going to continue this thread in case someone else has the same problem in the future. I also hope someone with more knowledge than me will contribute.

After further investigation, I've discovered that it isn't only my emails that have become randomly placed in the wrong folders. My subfolders also have become "shuffled" and are in the wrong folders and all my folders are in the wrong order. I also now have duplicate copies of most folders. This is probably NOT due to forcing Thunderbird to recreate MSF files because I've started each attempt at a solution with a "clean" copy of my backup, so nothing has carried across from previous solution attempts.

I have also found a lot of my folders and subfolders have been renamed with a string of letters and numbers (different for each folder). I found these renamed folders as long ago as a backup in August 2018. Yet somehow Thunderbird has still managed to display the correct folder names until the past few days.

With limited knowledge and no proof, I would suspect a Windows update may have caused the changed folder names. Thunderbird managed to hold onto its own folder data until the v60.? update in late January/early February. This must have "broken" whatever Thunderbird was doing to maintain accurate data. So this is when I became aware of problems.

I'm going to create a new profile so I can resume sending and receiving email. But I'll keep working on the old profile, trying to fix it. If I'm successful, I hope to import the email I can salvage using "ImportExportTools".

I intend to start by renaming my folders (those where I can access the emails so I know what the folder is). I'll try re-ordering them and deleting everything I can just in case malware is at the root of this (although my anti-malware hasn't found anything).

If they don't close the thread, I'll report back in the hope this thread may help someone in the future. Also, I'm still hoping someone may be able to help.