For both incoming (also referred to as "pop" or "pop3") and outgoing mail (also referred to as smtp) server, put :
If mail.yourdomain.com is not working (perhaps because you recently changed your domain's DNS), then you can replace it with the IP address or the hostname of the server which you are on.
The incoming port number is 110.
Any of the following outgoing port numbers should work 25 or 26 or 587 or 2525
These settings are the same for your addon and parked domains (when you are checking email for them and need to set up your account in your email client).