As of Wednesday, those who use a mail client on their Apple devices to connect to our shared mail services may be encountering an error regarding an SSL certificate mismatch.
This has been caused by the renewal of the SSL certificate that covers our servers' hostnames. The warning will display when your mail client connects using an aliased hostname (e.g. mail.yourdomain.com).
If your mail client doesn't let you 'Ignore' or 'Add an Exception' for the certificate warning, then you should change your settings to turn off 'Use SSL', or change the server address to use the actual hostname.