Question : Smtp Email Failure

Here is the situation.

I have a w2003 server running exchange server and iis all on the one box.

I have a piece of code that runs using c# and asp.net and this sends emails. If i send to another address within the domain of the w2003 server everything works great. My problem is that when i try to send to an address other than one on the domain i get the following:

The server rejected one or more recipient addresses. The server response was: 550 5.7.1 Unable to relay for <Account>@<OutsideDomain>  

Can anyone help?

Answer : Smtp Email Failure

http://forums.kayako.com/f84/how-setup-windows-2003-exchange-2003-smtp-relaying-14238/

   1.  Log into Exchange 2003 server (192.168.5.25 in my example above) and start Exchange System Manager.
   2. Expand the organization_name object, and then expand the Servers node. Expand the server_name object of the server on which you want to control mail relay, and then expand the Protocols node.
   3. Expand the SMTP node, right-click the virtual SMTP server on which you want to control mail relay, and then click Properties
   4. Click Relay.
   5. In the Relay Restriction dialog box, several options are available. The Only the list below option is enabled by default; the list below this option is empty.
   6. Click Add. Enter the IP address of the server running eSupport (192.168.5.80 in my example above).
   7. In the Relay Restrictions dialog box, click OK.
   8. Click Apply, and then click OK in the Default SMTP Virtual Server Properties dialog box.