Can someone help me? I just received a notice from someone telling me that he got 200 emails from a spammer on my server. The header in the email has no IP address, and even if it did, I do not know how that would help me because I am doing name based hosting. Can anyone tell me how to determine who is spamming?
I am new to Linux and am not sure how to look at the email logs to figure this out. It would be a shame if I were blacklisted for this.

Someone please help!

Thanks in advance,

David Harris