There have been a number of tips posted here on dealing with this issue (try searching on 'sendmail'), but today's Mac Resource Page has the best start-to-finish description of the process that I've seen yet. The MRP covers getting a domain name, configuring sendmailsetting up users, and getting a POP server running to handle the routing of the mail.
If you have a full-time Internet connection and want to handle your own mail, give Eric's MRP a visit today! After today, you'll have to search for the October 30th posting to find the details.

