Hi, 2 days back my friend had problem with Exchange SMTP, All mails are at Queue. As I suggested they have tried changing Gateway it went out but very slowly, Yesterday again they faced the problem. And this time it was problem only with sending Emails to Yahoo and AOL Domains. tried using Another Exchange Server which we build for testing from there also we are unable to send mails to Yahoo and AOL. And I found it the ip address they are using is in spam blocked ip ..and tht ip doed not have reverse dns entry... Please let me know whts the permanent solution and one more thing This server is our Internal mail server & SMTP server (abc.com) ...and already we have Other External mail server which will respond in the internet (abc.com) now how to set Reverse dns for exchange server And if we set is there any problem to the external mail server (Linux) .. Thanks in advance.....cheers