Routing mail to external

Dear All,

i have set domino server in a LAB, i have one firewall using ISA server, one server as domino mail server

all internal mail routing properly,

but i can not route mail to external. i configure “enable smtp used when sending message outside of the local internet domain” in configuration document.

on this server i can ping all external mail server. internet connection using ADSL no public IP.

do i need to configure anything else?

Could you please help me to solve this?

thank you for your help

Steven