A couple of weeks ago, on two different DNN sites (the only 2 I have), with completely different domain names, I started getting new user registrations (at about the same time) by users using either bad email addresses (authorize email bounces back) or they never actually complete the authorization.

If this was just on one of my DNN sites I would just think some somewhere decided to screw with me. But there's no way anyone can associate these two domains to each other.

So my questions are:
Is anyone else having the same issue?
Is there some kind of exploit that is being attempted against DNN sites?

Thank you.