Dear Frds,I have server 2003 R2 server configured with exchange. In N/W available Sonicwall Firewall with Static WAN Configuration. Since last some days i am not able to outside mails like from yahoo,rediff and other. Internally exchange working proper. Anyone can assist me that why it's creating the problem?

What errors are showing in your event viewer?

Hi Nupur, Looks like firewall is blocking port 25 so first thing, verify some of the external email domain (like yahoo, rediff..) communication manually on port 25 through telnet with below procedure. XFOR: Telnet to Port 25 to Test SMTP Communication http://support.microsoft.com/?id=153119

Can you telnet to port 25 of your Exchange Server from beyond your Firewall? What NDR's are fired back when trying to send to your Exchange Server?

Check if you can telnet your exchange server from outside of your firewallalso see what error you are having in the NDR, that would be key for troubleshooting.after having those info we can further resolve it.