Hi, We have recently had a major issue with Exchange Server 2000 after installing SP2 for exchange. There is a bug in the service pack that opens the exchange server to open relay. I have discussed this a number of technical people and it is a bug known to Microsoft. To solve the problem I have had to specifically use Reverse DNS lookup on all email and specify our domains and subnets to exchange, which is very CPU intensive . Even this does not close all the holes for relay only 7 out o 8 of the Abuse.net relay tests. Microsoft say it will be fixed in Service Pack 3. In the meantime I would not recommend installation of SP2 for Exchange. If you check this out it may help to stop loads of open relays from responsible System Admins like who will be unaware of what the SP will do to their mail servers. Sincerely Jason Richards Network Administrator