Thanks for the explanation Tim.
I haven't messed with running a mail server since 1999 so a lot has
apparently changed, and I am a bit concerned about doing it right.
Presently I am trying trying exim on a CentOS platform. It seems to
send out mail just fine, but when it comes to answering someone else
connecting to it from the general internet that is were I apparently
don't have something configured right yet.
Anyone care to create a nice write up :-)