Email Client Not Connecting - No Valid SSL

Sometimes, email clients, such as Outlook or Mac Mail, will give an error claiming that the SSL certificate cannot be trusted or is invalid.  This is how to check if it's a valid error or bug.

The error message may appear as one of the following:
The server you are connected to is using a security certificate that cannot be verified. Mail can’t verify the identify of the server mail.domain.com

or
The server you are connected to is using a security certificate that cannot be verified. The target principal name is incorrect. Do you want to continue using this server?

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Evaluate Potential SSL Error

1. Locate the incoming and outgoing server hostname you are connecting to in your settings in your mail client
2. Use SSL Shopper to check the SSL on the hostname
   1. If it shows a valid SSL with no warnings
      1. Restart the device
      2. Remove and then re-add the email account
         CAUTION: If connecting with POP, ensure copies of the emails on the account are saved in the webmail before removing the account.
      3. If the warning persists, it's just a bug, and you can trust it
   2. If the SSL is not valid or has warnings, review the warnings and resolve
      1. If using AutoSSL, renew the certificate
      2. Consider using the server hostname as the incoming/outgoing hostname instead
         TIP: You can find the server hostname in your Account Technical Details.
      3. If you aren't sure how to resolve any errors or warnings, contact Support
      4. If the certificate is valid, but the warning persists, trust it
         TIP: Outlook will sometimes throw the error even with a valid SSL. This is a known bug in Outlook; the best option is to trust it.
3. If all else fails, connect using the non-SSL settings