Prevent becoming a Mail Relay

Open Exchange System Manager.

Under Servers expand your servers and look around. You probably have a Default SMTP server, and maybe some others.

Right click your SMTP server and choose properties. Click the Access tab.

There are two settings you want to look at here. Connection and Relay. Connection controls access to the SMTP server completely, while Relay controls who can use the SMTP server as a relay. If you have any questions at this point click help!

The best practice here is to choose Only the list below. That way anything that is not explicitly allowed is denied. Add the IP addresses that need to use your server as a relay. In other words all your clients that send email using SMTP.

Also if you need to test your server for open relay (I highly suggest this) there are a couple of services to help:

I like to use http://ordb.org/

This was posted in the forum by tom11011:

[color blue]tom11011 (MIS) Mar 6, 2002
If you wish to test for relay, goto

www.abuse.net/relay.html [/color]