Yesterday I received an email saying something like "What is this about? Stop sending me email". The almost obvious intent was that I answered so they could validate my email account is active and I am silly enough to buy from spammers.
Today I received what seems to be a "reply to all" to the first email saying something like "Why did you accuse me of sending that email?"
So now the intent is to make the first email credible, so if I feel smart enough to help everybody else understand SMTP, but I am actually fool enough not to detect this is a scam, I would then send an answer.
But, I must say I haven't seen a scheme like this before. So, congratulations spammers! Cockroaches do not take evolutionary leaps this often.