Mac Mail is the default mail program for Mac computers. To setup your domain email on Mac Mail, please follow the instructions provided in this tutorial video.
The steps taken to find the email account settings for the first portion of the tutorial are for cPanel email accounts only. For users on the SmartMail system, your email account settings are available through the "View Email Client Info" link in Member Zone.
If you're logging into your Master Account, you will need to click the domain that you're trying to setup email for first before you can see the "Access Site Admin Panel (cPanel)" and "View Email Client Info" options.
Certain ports numbers and encryption settings (SSL) may or may not work depending on your router's settings and your internet service provider's network configuration. If you're unable to send email using the SSL encrypted setting, you can try using the non-SSL encrypted setting instead, or vice versa. The default port number for outgoing email using a non-SSL encrypted setting is 25. If this port doesn't work, you can try changing it to 587.