I am trying to send Emails from my ASP.Net web application to external Emails (yahoo, Gmail and all other cooperative Email domains) and getting following error message. "Mailbox unavailable: The server response was:5.7.1 Unable to relay" From above error message I realized that I have issue with Relaying. We have exchange server 2010 on Windows 2008 R2 Enterprise 64BIT Operating system. I checked some forums and found following link to enable relaying on Exchange server 2010 Technet I am bit confused on these settings on the Remote Network settings, should I need to mention all the external Email domains IP address? If yes, how can I get them? In bottom line, My application should send the emails to the external users who uses different emails (yahoo, hotmail, Gmail etc). How to enable this? Please help me on this. I have all the rights to our Exchange server (I am one of the Administrators in our IT department) Thank you, Raj Dreaming a world without any war in anywhere

Hi The remote servers field needs to list the IP (or IPs) of your internal web servers that will be generating the email. Those are the servers that need permission to relay mail out through Exchange. Cheers, Steve

Thanks Steve, 1. We hosted our web application to external web hosting server (go daddy). Do i need to add their IP address on the list 2. I am testing the application from my machine (Using my visual studio) also. In this case, should I put my machine network id also in the list? Please let me know Dreaming a world without any war in anywhere

No problem. Yes, you would need to add any IP that will send mail that requires relaying, however allowing a public IP which is probably shared between go daddy's other customers could open you up as a relay to all of those servers. If you have a dedicated IP there then it should be OK. Cheers, Steve

Try the below links out and see if it resolve your problem. http://exchangeserverpro.com/how-to-configure-a-relay-connector-for-exchange-server-2010 http://www.bunkerhollow.com/blogs/matt/archive/2010/03/14/allow-applications-to-send-email-through-exchange-2010.aspx Girishp

Hi, Any updates on this issue? Thanks, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Evan Liu TechNet Community Support