local IP - public IP - LAN with Zyxel 642R ADSL

hi,
I'm running a linux (mandrake9.0) web and mail server on a old pentium
300. the server is in a LAN with 2 windows pc's. all three machines
goes to a small 5 port hub form where a line is going to the router
ADSL Zyxel 642R. on the router NAT is active and my local pc's are
192.168.1.xxxx; the server is 192.168.1.69; the problem is I use the
laptop both home and around, and eudora is configured to use
smtp.mydomain.it; when I'm outside smtp.etcetc resolves to my actual
public IP and works fine; but when I'm home I've to edit the
windows\hosts file to enter a line

192.168.1.69 smtp.mydomain.it

to let eudora (and explorer) contact the server at the correct IP.
obviously every time I move (several time in the day( I have to
comment that line to let eudora resolve the external IP again).
The router defaults every port to the IP of the server.
Is there any way to configure everything so that I can access the web
and the mail even from inside my LAN using my public IP?

thank you for your help and your time

david