DH, I recommended that a few months ago. Unfortunately, that option isn't available. I've deleted prospective new members from the queue based on their usernames or email addresses being dubious. That's not always going to work, though, as a troll could easily register a perfectly normal name and use a bland email address.
I'd be all in favor of shutting down new registrations for a week or more, though.
Whoa my Hotmail account IS my main email. And I'm sure a lot of other people are that way.