We have a persistent issue with user's on a particular tenant using Apple Mail on there iPhone's.
The phone frequently pops up 'Cannot verify server identity'.
We've tried all the basic's people suggest for this error, Re-add the Account, Update IOS, Untick SSL etcetera etcetera
We though It might be linked to some DNS issue, DNS is hosted by another company and it had some unnecessary records in it which we removed, Made No difference. We also had them redo the SSL certificate just in case.
Open to suggestions to sort this, I think it may have someone to do with Apple Mail not trusting something. It's odd we are getting this with just this customer, and users having the same problem on their phones.
Thanks in Advance