Issues with Email on iPhone7
Continuously get pop-up saying: Cannot Verify Server Identity - The identity of "webmail.kuhncom.net" cannot be verified by Mail.
Email provider telling me it's a known Apple issue.
Is this true?
iPhone 7, iOS 12
I wouldn’t call it a know issue, but I have seen and heard of others having that warning before, usually it’s triggered by a certificate issue which may be on the device or at the ISP end.
You could simply try restarting the device, but the most successful fix is to delete the account and then re-add. If the issue is to do with the ISP server then when setting up you may still see a similar warning, but instead of just seeing two options (View and Cancel) you may get something like “Continue” or “Trust”.
Obviously if you select Trust you need to be sure you are actually connecting to who you think you are, but it may be the only way until the certificate problem gets sorted. Some have reported turning off SSL (which requires a different port number) can also stop the warning, but again you are reducing security in doing that.
The reason for this pop up as said above can be ISP or devices related, if ISP it usually gets sorted quickly and the dialogue disappears, if it’s device then it may simply be for some reason the iOS has forgot the setting and it now has to keep asking, the process of delete/add account sorts that out.
These discussions may be of interest.
Mail "cannot verify server identity&#… - Apple Community
iPhone cannot verify server identity - Apple Community
Hope some of this helps.