I keep getting this error and Mail wants to shut down and repair itself. However, it keeps doing it over and over. Does anyone know what to do to stop this?
Mail needs to repair its information about your mailboxes.
Definitely file a on that and report it.
Thanks for your reply. I reinstalled a clean copy of 10.12 on a 2nd drive on my laptop. I entered the mail accounts manually and things seem to be working ok right now. I think the problem is with the keychain syncing to icloud. If i recreate the entry it appears to clear up the problem. I disabled the keychain in icloud and will monitor this to see if it was the culprit.
This issue has cropped up again! So I reinstalled 3 times on a Samsung SSD and still getting this error every few minutes. Of course there is nothing that you can do but quit and reopen mail.
I tried on the last install to setup my IMAP accounts from scratch and did not connect to iCloud - which I had done the 2 times before. I have deleted the envelope files, cleaned caches, removed the mail folder in Library, etc., everything I could find.
Is anyone having this problem and knows what to do?
Found the answer! I have an email account with a company named "Enom". Their IMAP servers are NOT COMPATIBLE with the IMAP implementation in Apple Mail. Once I took care of that, everything works well!
May I ask how you took care of that? Thanks
Had to connect to the incompatible account using POP. No problems after that. Enom blames it on Apple and visa versa!