domain change

[Debian Ghost <debian@ghost.ntelos.net>]

Hey Guys,
I posted this question earlier in another way, but no one replied to it.
Maybe if I ask in another way:

I changed the domain name of my machine (via DNS) and was wondering
if there was a global file that I need to change to tell my machine it is

host.new.domain rather than host.old.domain.

I changed the exim.conf file (sendmail) but when I telnet into my machine,
somehow exim still thinks it is the old name even though I changed the
conf file. Is there any global file that I need to edit to get rid of the
old.domain and tell the machine it is new.domain?

Thanks a lot!

D. Ghost