No idea what happened, but the INBOX folder in my Thunderbird email client lost everything. All of the subfolders are just fine, only the INBOX was lost. The emails that disappeared locally also disappeared at the IMAP server. I have spent two days with every "fix" known to man and cannot get the old emails back. But I have a copy of the old INBOX folder that is 100X larger than the current / new INBOX folder. I have looked at both files, and certain the bigger file has the old emails. I have tried all sorts of swaps, etc, and Thunderbird never likes it.
So what I want to do is copy all of the copy / old INBOX data into the new one. Will that work? If I do it, do I need to delete the INBOX.msf folder so Thunderbird will rebuild it? Anything else to be careful about?