Is the folder located under "local folders" or as a part of another account? If another account, is it IMAP or POP? On the assumption it is under local folders. Help menu (Alt +H) > troubleshooting information Press the show folder button. (Everything from here is outside Thunderbird. You might close it to prevent confusion of terms) Open the mail folder. Open the "local folders" folder There should be a collection of files. for example trash and trash.msf If you have folder there that contains other folders you will also see sdb folders. So as I have folders in my trash I have a trash.sdb folder. Of the three, the file without the extension is your mail. The msf file is an index that also contains tags. If you do not use tags deleting it will result in it being recreated when Thunderbird starts without data loss. Opening the sdb file if it appears will take you into that folder and it's sub folders. So to your original question. Yes you could recover just that file from a mozbackup. Probably best to rename the pvc file to Zip and usae a zip utility to get just that file from the archive, but in reality I think you will find the file is already in the folder (sometime they just do not display.) If the file is still there but simply not showing. Return to the original folder you opened from Thunderbird. (the one with abook.mab, your address book, in it) and delete the foldertree.json file (make sure Thunderbird is not running). It will be recreated when Thunderbird starts, but startup will just take a little longer than normal.