Hi Ravikanth, > I had a DSL Broad Band internet connection. Internet is connected > through router. In router through nating all pc in the LAN is getting > internet. We dont have any public ip. WIth out any public ip can we > configure Exchange in our network or not. If so where we need to change > the settings. How do we need to do SMTP and DNS configuration. First you will need to confirm from your provider that your public IP address is a static IP, not DHCP or Dynamic. This is *very very* important. If your public IP is dynamic or DHCP you are out of luck, sorry (yes you can wangle it using dynamicdns or similar but you are on your own). If your public IP is a static IP then you need to configure your firewall to connect incoming port 25 (and 53 if you want DNS) to all go to the NAT IP of your Exchange server. If you have external users outside your LAN who want to check their email from the Exchange server you will also need to redirect ports 110, 80 and 443 for POP3, OWA, OMA/ActiveSync, and RPC/HTTP. best regards Mike Salim.