If you are on Mac OS X El Capitan (Version 10.11.x and below) and using Apple Mail – They are not officially supported by ourselves. As you are not able to connect the email servers via SSL/TLS. This is because they have not been updated to support TLS 1.1 or above and this may cause you to have trouble connecting to the email server successfully using secure email settings.
You can check what macOS version you are on by clicking the Apple logo in the top left-hand corner of the screen and clicking on “About this Mac” and it should inform you of the version you are on.
We would recommend if you are able to update your Mac to a more updated version of macOS where you are able to connect to the email server using the SSL ports. Otherwise you will have to use the webmail located at: http://cpanel.iracknet.com/webmail