cPanel support both POP3 and IMAP. You would use "mail.yourdomain.com" for the incoming and outgoing mail server and you would use "firstname.lastname@example.org" as the username. Note this is a FULL e-mail address for the username.
For those who don't know the difference, well POP3 protocol will download your emails to your local email client where IMAP will "connect" your local email client to the server directly, all mail resides on the server, so you can connect up from another location perhaps by way of webmail etc and still have your messages there. Also, connect time is very quick as with IMAP all that takes place on the 1st-time connection the download of the message headers which is pretty quick and dirty VS a POP3 connection that would need to download your entire mail queue.