[Exim] I can send mail, but can't get mail.

I can use exim on my machine and send mail, but if anyone tries to send
to me it
wouldn't go through. I've tried to telnet to port 25 from an outside
account, and get
the message: Unable to connect to remote host: connection timed out.
If I try to connect from the "exim" machine, I'll get through, or if I
try to connect from the local subnet. Is there any suggestions. I'm
sorry this mail should probably not go to this list, because I don't
think it's a exim problem.

Sigurd Stordal
Major in experimental Petrology
University of Tromsoe