Email Forwading

I am using Microsoft Exchange server-2000 corporate edition. Since the sever is in local network; due to security issues I can not give public access to the server from internet, those they need access to the Server from home should dial up to the office. It can receive Email from public SMTP servers by means of email gateway put in the DMZ zone.
Now the problem is, people going outside of the country can not check email; since they are unable to make dial up connection. Can anybody help me toforward email receiving to his mail box to any other mail server like yahoo or hotmail