Did you move your Thunderbird Profile to the new computer correctly?

The correct way is to: 1. Close Thunderbird. 2. Create a new profile in the desired location using the Profile Manager. 3. Exit the profile manager. 4. Delete the contents of the new profile folder that you just created. 5. Copy the contents of the old profile folder (its files and subfolders) into the new, empty profile folder. 6. Start Thunderbird.

See Create a new profile and copy the old one over it for details.

Yes, thanks, I did all that, exactly as you described. My other profile transferred correctly, but this one only partially, as I described above.

Is your backup of the profile intact, not touched? If so, then we can try to recover your lost folders from it.

First some learning:

Let us say that under Thunderbird's "Local Folders", you have a folder with name "Stuff". Under "Stuff" you have a subfolder under it called "Things".

On the hard drive you will see a file called "Stuff", a file called "Stuff.msf", and a folder called "Stuff.sbd". Under the "Stuff.sbd" folder you will find a file called "Things" and a file called "Things.msf".

The files "Stuff" and "Things" contain all the e-mails that are in those Thunderbird folders. The files "Stuff.msf" and "Things.msf" are indexes, used by Thunderbird to keep track of the messages in the main files.

What you should do, is first in Thunderbird create a folder under "Local Folders" called "Recover". Then create a folder under that and give it any name you want. This is to force Thunderbird to create a hard drive folder called "Recover.sbd".

Quit Thunderbird.

Copy (not move), files from your untouched backup of the old profile, to the hard drive folder called "Recover.sbd".

The files you want to copy are the ones without the file extension, that are the ones for the folders you are missing in Thunderbird. Do not copy the .msf files.

Try it for a couple of those files, then start Thunderbird and see if the e-mails you are missing show in the "Recover" folder.

If this works, then continue on with the rest of the files. Do not have Thunderbird running when copying those files on the hard drive.

You can copy the .sbd folders over to the "Recover.sbd" folder, but make sure that the .msf files do not exist under them before starting Thunderbird again. We want Thunderbird to rebuild these .msf files.

Excellent! With a little tweaking, that's got it!

The tweaking because:

1) Creating a "Recover" folder in Thunderbird didn't create a "Recover" folder on disk, just "Recover" and "Recover.msf" files. But I created the "Recover.sbd" folder manually and after that it worked.

2) Everything went smoothly for mail folders with names in English. I was able to recover the mail folders with names in Russian by renaming them.

Once everything was recovered, I tried renaming folders inside Thunderbird, giving them names in Cyrillic. It worked, but they show up on disk as files whose names are alphanumeric strings not obviously related to the Russian version that displays inside the program.

The important thing is that all the emails were recovered! Once again, thanks a lot!

1) Creating a "Recover" folder in Thunderbird didn't create a "Recover" folder on disk, just "Recover" and "Recover.msf" files. But I created the "Recover.sbd" folder manually and after that it worked.

That's why I said: " create a folder under "Local Folders" called "Recover". Then create a folder under that and give it any name you want. This is to force Thunderbird to create a hard drive folder called "Recover.sbd". "

Once everything was recovered, I tried renaming folders inside Thunderbird, giving them names in Cyrillic. It worked, but they show up on disk as files whose names are alphanumeric strings not obviously related to the Russian version that displays inside the program

While I am a Windows computer technician, I've never seen a computer that used Russian. I don't know if Windows will accept Cyrillic for file names.

If they were Cyrillic before, but not now, maybe it's because you don't have the locale & language settings for Windows set for Russian?

Whatever. I'm just glad that you have your missing e-mails.