Thread: New User Registration Challenge-Response Spam Filtering

New User Registration Challenge-Response Spam Filtering

Is there any "New User Registration Challenge-Response Spam Filtering" system (or anything like it) that would send out an email to an alleged new user and ask them to verify their registration? I don't know about anyone else, but I am getting about 15-20 junk registrations on my site per day and it is a bit annoying. Just a simple question such as "What number comes after 5?" or even a capicha entry sent to verify to their address. Even a link to verify would cut down on some amount of spam.