My head hurts slightly from trying to parse your comment. I realize English probably isn't your first language, but I think you should try and rephrase it if you want to be understood.
More concisely, he/she wants to be able to discover a user's email address when they visit a site, so that the user just has to click a "create an account, and email me my password" button. (i.e. removing barriers to user sign-up to his/her site) This obviously conflicts with the idea that a user should be able to keep that information private.
