Question : exchange 2003 being used as a spam relay

Hi all, I think starting yesterday our server is being used to rely spam. It's been placed on a few blacklists. The server was super slow to work on and I saw the cpu spiking at 100% for minutes at a time. When I shut down the SMTP service the cpu is now normal and the server responds normally. A few of the blacklists say that the server has been sending out virus emails.

The question is, what can I do about it? It's exchange standard 2003, service pack 2, what else can I do to stop the rely? The server has been in operation for a while so I'm not sure why all of a sudden this happened. We have symantec endpoint running on it and it has found any threats so I'm confident there is nothing on the server.

Any help would be appreciated.

Answer : exchange 2003 being used as a spam relay

Start with my spam cleanup article:
http://www.amset.info/exchange/spam-cleanup.asp

That will help you identify what method has been used, securing it and cleaning up the server.

-M