Thunderbird asked to compact folders saying it would save hundreds of MBs of disk space, I accidently clicked "compact now" instead of just ignoring it as I usually do. A… (read more)
Thunderbird asked to compact folders saying it would save hundreds of MBs of disk space, I accidently clicked "compact now" instead of just ignoring it as I usually do. As a result, Thunderbird deleted all mail on my Inbox folder - after restarting Thunderbird, my inbox was empty, I also checked the mail folder on my file explorer and the "Inbox" file (no extension) was just a few KBs, whereas previously to Thunderbird deleting it was several MBs. There were no errors reported during the "compact" process.
I don't think I can recover the mail that Thunderbird deleted because the mail server does not seem to keep mail older than 12 months. One of the reasons I used Thunderbird was to be able to keep a local copy of older emails.
The pop-up I received was the one shown in this article by Mozilla: https://support.mozilla.org/en-US/kb/compacting-folders
The article explicitly says "compact" does not delete mail, but then explains that it actually does (by not moving mail "moved or marked as deleted" to the a new file, and deleting the old file). I had no such "marked as deleted" mail. It was just plain read mail on my Inbox folder.
This is an Office 365 POP account. Thunderbird's retention policy for the Inbox folder was to use my (Thunderbird) account's policy, which was to never delete any mail. Alas, when I hit "compact now", Thunderbird deleted all my mail. I was running Thunderbird 91.6.1 on Windows 10.
I tried making a backup of all Thunderbird related folders and deleting the "popstate" file to download all mail from the server again. Mail got downloaded, but not all - as I mentioned, the mail server only returns 12 month worth of email, whereas I had years of mail stored locally. I don't see any way of recovering it... Why would Thunderbird just delete all mail calling it "compact"? Makes no sense...