This is our setup: We have a W2K DC with NAT behind the WAN router. I have setup Exchange on a member server on the internal network. At present we were using this for internal calendar sharing and threaded messages. Our email is hosted by our ISP. Now I need to be able to share the calendar remotely and I assume we will eventually host our own SMTP mail. So: 1. If our domain name is xyz.com and the MX and A records point to mail.xyz.com on the public DNS server ( this would be our ISP's mail server); how could we run a real time pilot with our exchange server on the same domain and still receive mail from our ISP hosted mail. Obviously once the pilot Exchange works well and we have tested bandwidth, we will eliminate the ISP mail server. 2. Since our DC hosts NAT and points to our router's public address, would the MX record in the public DNS for our Exchange server also point to our router's public address? I have some trouble understanding how to route the Exchange through the internet. Would it be simpler to use a second network card in the Exchange server and assign a public address to that? Thks, Dianne