I have mail enable on my server which I've configured with no problems. All seemed to work after I repointed my MX records of my domain to the ip of my server.
When setting up my e-mail client on my laptop to send and receive the e-mails I used the IP address of the server I have for both incoming and outgoing mail servers.
It does work but not totally as some servers such as gmail reject e-mails from my mailserver as I have put the IP address as incoming and outgoing.
What do I need to do on my DNS server to setup names rather than IP's