Undo delete / move to trash in Thunderbird

Solution 1:

In my experience (I also just tried this with two different IMAP accounts):

1. Pressing Delete when I have selected a message in my INBOX moves the message to the Trash folder.
2. Pressing Ctrl + Z does move the message back to the INBOX.
3. A message in the status bar confirms something has happened: "Deleted 1 message from Trash".
4. However, the view is not refreshed right away, and I still don't see it in my INBOX.
5. I either wait some time or I explicitly trigger a refresh by pressing F5 or I select a different folder and then go back to the INBOX.
6. The deleted and subsequently undeleted message is shown back in its place after a second or so.

Ctrl + Z also works if I visit a different folder after deleting the message. In that case, going back to the INBOX triggers a refresh and the message reappears.