I'm not a fan of this idea:
From a user experience point of view, it's much more effort (at least 3 clicks more) to have to open an email client, open an email, and click a link, as opposed to just entering a password.
Also as airlinenut mentioned, it would allow others to send you an annoying email just by entering your email address, and any methods to prevent this (captcha etc) will just make it even harder for the user.