[Exim] Internal Mail Server

Hello,

I am new to the list. Here is my current situation. At my place of
employment our ISP takes care of our mail. The mail goes out to the isp
and is directed from there. If someone at a cube or whatever wants to
mail someone a message in the same office the mail goes out to the isp
and back in. I am new at this place and the whole idea of what was
going on immediately brought thoughts of qmail or exim. I built a
FreeBSD box to use Exim on. My question follows:

Could someone help me out here, Basically i want to use Exim for an
internal mail server and have exim pass out all external mail. There is
just one domain name. It should be fairly easy yet i haven't goetten
anything working at all. Are there any sample config files or are
anyone on this list currently doing this now ?

Thanks

Matthew Bettinger