How do I stop my Exchange 5.5 being used as a SPAM relay host? – Wayne Small

To avoid being used as a SPAM relay host, you need to ensur ethat you have the current Service Pack for Exchange Server 5.5 (currently SP4). Also check out the Microsoft articlehttp://www.microsoft.com/TechNet/exchange/relay.asp which provides key information on disabling relaying.

To test the results of your modifications, you can from the server, TELNET to mail-abuse.org on port 23. They will test the system and report back to you to indicate your relay status.