.mac in mail recieving mail issues

Hey

I have just set up my .mac account in mail. I set up the account using the POP Account type and my ISP's out going mail server and i can send mail fine....but i cant recieve mail using mac.mail.com as my incomming server.

I then changed it, so i was using my account type is .mac and with this i can recieve email, but not send

Does anyone have any ideaS? i want to upgrade my account to a full membership, but not if i cant resolve this issue

Many Thanks