Our ISP has blocked use of our send ability. presumably someone is relaying SPAM through our server. I have checked all AV and malware software is up to date on each of our clients (about 15) but the SPAM is still being queued. Is there a way to find where this is coming from as they wont give us a connection until it is resolved. The messages in the Exchange queue all have the from address as <> and they are all SPAM. We are generating about 100 per hour.
Is it worth changing the user passwords on the server ?
Is it just a server issue or could the clients be causing the problem - if so would disconnecting the clients help the problem ?
I am not overly technical so if anyone is able to offer any suggestions please keep them simple.