I was wondering that too, but I was thinking that at some point that would take human interation: 1. i reply back and say thank you 2. they register for an

I was wondering that too, but I was thinking that at some point that would take human interation: 1. i reply back and say thank you 2. they register for an account 3. i approve them and then they start spamming Maybe a Mechanical Turk type thing?