Bad news, I'm afraid. You need to understand how gmail do IMAP. All of your messages are stored in one big heap, also known as All Mail. Each message is tagged. When you select a folder, it simply asks gmail to display just the messages with the tag that corresponds to that folder view. Hence one message can have many tags and so appear in multiple folders. This makes it a lot more efficient than regular folder-based systems, where each appearance in a folder would imply a separate copy of the message. So in the gmail system, a message with 5 tags would appear in 5 folders. In a folder-based system, there would be 5 independent copies of the message, one in each of the 5 folders. In gmail's system, when you delete a message it is tagged as deleted and normally disappears from view, though usually it remains in All Mail. Hence when you deleted your All Mail folder, you deleted your core message store. The deleted messages aren't in Trash, because Trash itself is in all probability in All Mail too. (Whilst you can set Thunderbird to use its own Trash folder and not All Mail, what you're describing suggests that you didn't do this.) I normally advise Thunderbird users to unsubscribe the All Mail "folder". It is usually just an unnecessary distraction. If you hadn't been able to see it, you would probably not have attempted to empty it. https://support.mozilla.org/en-US/kb/thunderbird-and-gmail