Question

Assumption: this is an internal web server

Is there anything special you have to do to get Windows 2003 to act as an anonymous SMTP relay server? I have configured many Windows 2000 servers to do this in the past and never had an issue.

I remember in Windows 2003 Microsoft went a little strong with the security… So is there any special registry keys you have to remove to allow this?
Some policy you have to remove or check for?

I’m currently getting this error: The server rejected one or more recipient addresses. The server response was: 550 5.7.1. Unable to relay for [e-mail]

Answer 1

In the Access tab of the smtp virtual server, there is an a relay button, in here there is a box with the option to select only the list below to relay or all except the list below.

If you want to make it an open relay, then select all except the list below and leave the box blank. I’d probabley suggest instead using the only the list below, and adding in the IP of the computers you’d like to be able to relay.

Theres also a tickbox that says Allow all computers which successfully authenticate to relay, regardless of the list above, if you tick this then anyone who succesfully authenticates to the server will be able to relay anyway.