A mail client running on an Apple device will require you make an exception if the SSL certificate provided by the server doesn't match the hostname you’re connecting through. If this SSL certificate is changed or renewed, which will happen at least once a year, another exception would need to be made.
By default, if you utilize your own domain name (e.g. mail.yourdomain.com) with SSL enabled this will show a warning like: Certificate Mismatch. The recommended method of enabling secure connections would be to connect using the settings provided in the articles below for your preferred connection type:
Most mail clients will allow you to either ignore the warning or provide an exception. Apple devices should let you do this the first time you connect, but when our SSL (*.extendcp.co.uk) renews, Apple devices will show another Certificate Mismatch error similar to when you set the mail account up, but won't allow you to ignore the warning.
Or you can try to add another certificate exception manually via Keychain, but this isn't something our teams would be able to provide support with.
Article ID: 730
Created On: Wed, Mar 20, 2019 at 1:26 PM
Last Updated On: Mon, Dec 20, 2021 at 2:20 PM
Online URL: https://www.heartinternet.uk/support/article/ssl-warning-on-apple-devices-when-connecting-to-mail-server.html