As simple as that. I registered at the website g2play.de some time back to buy a computer game cheap, and since I use fresh eMail addresses for each service where I register, I can say without a doubt that somehow, g2play leaked the eMail address I provided. I received targeted spam to that particular address today and there is no way this eMail address could have gotten into the hands of that spammer by any other means. Shame on you, g2play.