EC2 is a big issue for a lot of things. For example, while I was maintaining a credit card donation form for a non-profit, a large chunk of fraudulent submissio

EC2 is a big issue for a lot of things. For example, while I was maintaining a credit card donation form for a non-profit, a large chunk of fraudulent submissions came from EC2 addresses - actually more than came from African ISPs. So I too blocked the whole of EC2; the logic is pretty straightforward, in that a legitimate customer originating requests from there is highly unlikely compared to the other options.