When you open "Local folders.sbd" and then all the six *.sbd folders at the top one after the other, all of them are empty? But there are also mailbox files in "Local folders.sbd" (such as ACX, Adobe, Amazon, AmEx, Authors Guild, Book Club, ...ect ect) which have size between some MB and 92 MB. How can you see that they are empty ? To be sure: please post a screen shot with the contents of "Local Folder.sbd"

These all say 'file folder' but there's nothing in them.

I am going mad, damned AI!! And what is in the other folder on the same level, named "Local Folders" without the suffix .sbd?

This is the other folder

Much better! I still wonder how you were able to create these hallucinant Local folder hierarchies. Let's try this one but first thing to do is create a backup copy of these Local Folders and save it in your documents.

As usual all following actions must be executed while Thunderbird is closed: copy the Local Folders (shown in your last image) to your Desktop. Go back in folder Mail, rename Local Folders in Local Folder-old and drag it to your Desktop. Now verify that there are no Local Folders left in your Mail folder, then drag & drop the "real" Local Folders from your desktop in folder Mail. Restart Thunderbird and tell me that I can go to sleep.....

The folder with the 2 subfolders?

If nothing else, I've become much more proficient at creating screenshots. If you'd rather take this up tomorrow, I think you've put in plenty of time today.

The folder with the 2 subfolders?

Hugh??? I mean the "Local Folders" folder shown in your latest screen shot. The one which is on the same hierarchy level as the folder "Local Folders.sbd". You remember? (see image)

I think I need to wait until tomorrow. The more I try to follow the instructions, the more confused I get.

Again, thanks for your help.

OK -- almost there, maybe. What is the "real" Local folders folder? I have a backup, the Local Folders, and Local folders old.

Which one do I put back in Mail?