Have Exchange 2010 has been running fine, no issues.
Got call from client, cannot send.
Checked MX Toolbox
Listed on SORBS, Spamhaus Zen, CBL
CBL says trojan or botnet is on network
Checked server, Queues are not filling up with outbound mail, thus I don't think I have a compromised user account and not relaying, that I can tell.
I am in charge of the server side of the house, what are the steps I should take to verify the server is not compromised.