Below is a typical example of a MacMail settings screen to work with our SmarterMail Mail servers.
In the screenshot below, the place where most users slip up, is with the Ports and Authetication Type.
INCOMING MAIL
PORT: 993
AUTH TYPE: TLS
TLS: Ticked
OUTGOING MAIL
PORT: 465
AUTH TYPE: TLS
TLS: Ticked
Click Here to See Port Settings