Open Relay

This article shows how to configure an Exchange 5.x server to stop an open relay.

http://www.exchangeadmin.com/Articles/Index.cfm?ArticleID=7696

There are no spaces in that link.

Also if you want to test to see if you have an open rely or see it the fix works, go to this site.

http://ordb.org

Use the link on the top left to test your installation.

im using exchange 2000 and had a nasty experience with open relay before. i fixed the problem by doing the ff:

1) create two smtp virtual servers (server1 and server2) and add both to your smtp connector

2) server1 is configured to accept mails only. its ip addr should be your external ip. it should not be able to relay and no external dns are configured.

3) server2 is configured to send mails only. its ip addr should be your internal ip. it is configured to relay and external dns areconfigured.

with this setup, only those within your organization can relay and nobody from outside can.