Suspicious MailCatch Registrations

My blog is relatively new and I haven’t gone too much out of my way to publicize it, until I get some more content published. I’m getting roughly one new user registration a day and about 90% of the registration’s email address is from mailcatch.com. I did a little digging and found out that I can use the email address at mailcatch.com to look at everything that has been sent/received from that address. Not very secure on their part but it gave me an opportunity to take a peak at the user’s activity. It seems these mailcatch users are registering at many different WordPress sites. I’m feeling that I/we blog publishers are getting set up for some kind of hack or spam attack. Anyone have any insight on this?