Fixing corrupted Thunderbird mail data

I was beginning to get too well acquainted with the Mozilla Quality Feedback Agent when my Thunderbird kept crashing randomly while either:

• loading emails
• viewing emails
• deleting emails
• completion of email downloads
• and even upon closing of Thunderbird

It then began downloading the same email more than once after the crash, so I was getting annoyed at cleaning up after it.

Luckily, I found a way to fix it. As always, its a good idea to make a backup before making any changes.

As Thunderbird was still in a usable state, I right clicked the account which I suspected was corrupted and viewed the properties. On the "Server Settings" page, open up the "Local Directory" folder in Windows Explorer.

Now would be a good time to close Thunderbird.

Once in this folder, search for "*.msf" files and delete them. Don't worry, they are not email files, just index files which makes Thunderbird work faster.

Fire up Thunderbird again and view all your folders (ie. Inbox, Sent, Trash, etc). If you have alot of emails, it should take some time to rebuild the index files from your existing email data.
If you deleted the index files from the corrupted inbox, then Thunderbird should be working fine.

If Thunderbird is still crashing, you can either continue hunting down the rogue account by deleting the index files for a specific account one by one, or you can delete ALL index files on ALL accounts. To do this, go to a "Local Directory" for one of your accounts, but backtrack up one folder back to the "Mail" directory and perform the "*.msf" search from there.

If all else fails, try emptying your "Trash" folder.

A few reasons why Thunderbird may have been corrupted are:

• Power outage.
• PC rebooted without closing Thunderbird properly.
• Emails with strange formatting or structure, causing unreadable data to be added to the index file.
  

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