gd2shoe's Journal: non soliciting spam?

I just had an unusual occurrence. I'm posting here to solicit opinions. Please tell me what you think about my hypothesis.

I just received an email to my account for one Darby Candi (I found this in the header). This is in my yahoo box by the way. Well, my name is not Darby. All the message said was: "interesting observed". The return address is:"Samuel Luanna"

So I assumed that "Sam" had made an error and had sent his message to the wrong address for whatever reason. But when I sent him a brief reply, the message bounced (unknown account). Upon closer examination of the original header, it appears he had replied to me. While it's hypothetically possible for him to reply to a spoofed message (I've had at least one virus spoof my account), and then quit his service, I'm thinking there is a much more devious (and realistic) explanation.

I'm wondering if some services (yahoo perhaps) are creating blacklist of spam accounts, and not just email contents. Could pretending to send out emails to mistaken addresses be a way to give the account a partially clean record? Something else along these lines perhaps? Does yahoo use spamhaus or such? Any theories would be appreciated.