I have just installed Windows 2003 Small Business Server R2 with service pack 2 and set up Exchange Server 2003 with Service Pack 2.
The domain is a private name and I have set up SMTP on the Exchange server.
It sends SMTP mail direct to the Internet using the SmallBusiness SMTP connector.
It receives mail from a public IP that is NAT translated behind a firewall.
It all works fine and I have tested it externally to check that it does not allow relaying (over a dozen different tests) an is okay.
I have turned off Non Delivery Reports and only recipients in the domain can receive mail.
My problem is that the server is sending out very large quantities of junkmail to other people and I can't seem to see where it is coming from or how to stop it.
There are currently over 1500 queues at the moment and 99% of them are junk.
The other day it was so bad that the exchange server stopped receiving mail because the queue had reached nearly 100,000 messages.
Anybody any ideas, I don't think it has been hacked, is it a virus or what?