"do a quick email confirmation". And what happens if one or more of your users gets targeted for a long period of time ? You will force them to open there inbox

"do a quick email confirmation". And what happens if one or more of your users gets targeted for a long period of time ? You will force them to open there inbox every time they want to log in your site ? And this gets even better if they target your site generaly, it will be a lot of fun for the majority of your userbase to have to do that "open inbox" step, bet users will love it :) Sorry mate but your method sounds easily exploitable ... heck using reCaptcha would be less punishing for the user than your approach.