The rest of this post will be irrelevant to you.
However, sometimes you delete from the trash and realise later "oh shit! I needed that!"
To retrieve a deleted email from Thunderbird, you've gotta pray that you haven't compacted your data files since the email was deleted.
Next, go to your "Account Settings" in Thunderbird and view the "Server Settings" for your account.
Copy the "Local directory" path and view in Windows Explorer.
Note:Close Thunderbird and make a backup copy of your files before modifications.
If you have more than one email configured to one hostname, you might have to do some snooping around to figure out which one is the right folder.
If you remember the name of the folder which the email was in (usually Trash), then simply open the "Trash" in Notepad (not Trash.msf).
Search for the email somehow (ie. the sender address, email title, some content fragments, read throug it all, etc).
When you find it, look for the "X-Mozilla-Status" for the email you wish to retrieve.
Normally the value is "0x0009", meaning "Read" (MSG_FLAG_READ) and "Expunged" (MSG_FLAG_EXPUNGED).
Change the value to "0x0000" and save.
Load up Thunderbird and view the Trash. Hopefully the email should be visible again.
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