This has occurred because of how Apple manages and stores its SSL Certificates. These SSL certificates are what clients of their's use to connect securely over SSL to email servers. When email providers like ourselves renew their SSL certificates every other year, as we just have, this results in a different certificate being on the server than is being stored on the Apple device itself. Or to more plainly put it, a certificate mismatch between your device and our server. Ultimately, this produces the issue & error you’re experiencing.
To resolve this, follow these few simple steps.
1) Look up what email server you use. To do this, visit https://mxtoolbox.com/SuperTool.aspx#. Type in your domain name in the open text box. Then click the button which says MX Lookup.
2) Now, look at what server is returned as your mail server. In this example, my mail server is maila5.newtekwebhosting.com
4) Find the section for “incoming & outgoing” host/server and then locate this section on your device in the corresponding article. 5) Change the incoming & outgoing host/server from mail.yourdomain.com to the server which was returned in section 2. In our example, I would use maila5.newtekwebhosting.com
6) Make sure to do this for BOTH incoming & outgoing.
7) Finally, save or finish.
8) This should take a few minutes to verify the settings. If you receive any popup regarding whether you want to accept the certificate, please make sure and select Accept.
If you run into any problems or get any errors when doing this, please reply to this ticket or give us a call at 1-877-323-4678 opt 4.