We are being blacklisted by 9 different blacklist companies according to mxtoolbox. They include; Barracuda, CBL, Choon, ivmSIP, LASHBACK, NIXSPAM, SPAMCOP, Spamhaus Zen, UCEPROTECTL1. Not long after I discovered the problem this morning I had a user call and say their computer is basically under attack. I have shut down the computer. What is the best way for me to verify that it was this computer causing the issue?