Samsung Note 5 dual sim SM N9208 email issues

[globalminer]

I love this phone and everything worked fine till the update to Android 6.0.1.

Now, on only 1 of my 2 email accounts, I delete mails and then they reappear within a few minutes
The only way I can beat this currently is to reduce the sync frequency from "when received" to eg 15 mins and then empty the trash

Both accounts are IMAP

I have emptied the email cache, done a factory reset but still have the same issue

Ideas please

Regards
Nick