Mac Mail App does not save new smart mail boxes, brings back deleted ones, and simply does not work

Thanks will try that. Since there is no visual feedback as of the export is still running, but I can see "temp" folders still being created and changing to (same folder name but no temp) I guess it will take a while, I have a couple hundred thousand emails.

Will let it run a day or so and then check those steps.

Any reason I need to boot into safe mode to re-add my accounts? (Press shift key and ...)

As soon I reopened the mail app, it had no Smart Inboxes. Good. I set up a new Smart Inbox. I closed mail. As soon I reopened it, not only was new smart box not there, but "Today" was there. Just like it was before the entire operation.

There is to say, some of the steps did not go as outlined:

> Any files or folders that say “Mail” or “com.apple.mail”, select, on the top menu select File > New Folder (With Selection), then press Return.

This created a new folder, indeed, but inside that folder, instead of the 5 "Mail" folders that I had found and selected, some other folders where added. God knows why. I tried twice, twice same result. I select "Mail" and it puts some totally different folders into that new folder.

> Open the Cache folder and delete anything regarding Mail or com.apple.mail.

There was no such folder, but a folder named "Caches" (with an s). I opened that, there where no "Mail" related items inside.

So I just proceeded.

As I restarted, it asked me to import some messages on opening mail. I said ok. and there then I saw NO smart boxes (good) but as soon I added my own smart box, TODAY appeared, and mine was gone on restarting mail app.

I can't even rename that TODAY inbox. As soon I close, reopen, it is all as it was before.

I do have only one rule setup in Mail > Preferences > Rules. It basically trashes and deletes and marks as read only one specific "from". Even so, this shouldn't cause an entire smart inbox to disappear and a TODAY to appear. But the rule is really not connected to any of the rules I set in my smart boxes.

Will try the next steps after it finishes downloading the 150K emails since I have now re-added my IMAP accounts to MAIL. I will let that finish first.

New user account does not present this issue.

Will be trying the steps recently recommended (hey, another user with "similar issues") in the last reply on the thread here.

And now the inboxes disappeared while it was downloading messages, so, I did not even close the app.

LOL.

I mean, literally, this is impossible. Can anything work at all?

Tried terminal too. Nothing. Same issue.