IMAP issues with Apple Mail

I'm having major issues with Apple mail crashing as soon as it opens with various email accounts.

All these accounts work perfectly on MS Outlook (which I really didn't want to use, but I am having to).

Gmail, Icloud, Hotmail accounts seem to work ok, but I have a few other email accounts for work that just crash the App as soon as I add them as an IMAP account.

If I add the same accounts as a POP account they are fine, so it's only IMAP that has the issue and ONLY with Apple Mail.

I've seen a few reports from other people who have the same issue and I have it on multiple machines, iMac, Macbook Pro, Mac Mini. All at different versions of OS (based on the age of the machine), but the bug is common to all.

I've tried the recommendations of removing accounts and re-adding, safe mode, etc... even down to removing the files from specific folders and restarting for a fresh build...no difference.

It would seem that Apple has no idea either and there's no way to find out whats happening from their failure file either.

Anyone having the same issue?