On 22/03/2016, Enlighten Hosting renewed the security certificate for mail.enlightenhosting.com
In this process, we also changed certifying authority.
It has come to our attention that some older mail clients do not have the associated root certificate installed by default, and therefore may alert users as to a certificate problem.
The Certificate however, is valid.
Here are the details of this certificate:
Common name: mail.enlightenhosting.com
Certificate Authority: COMODO RSA Domain Validation Secure Server CA
This certificate can be trusted, and it is safe to click "trust", "accept" or similar when challenged about it.