[xwiki-users] User Screening at registration

Hello, I'm running a new installation on a public address. However, I'd like to screen new users. That is, new users insert their username and email, and I get a notification. Then they get a confirmation email only if I approve the user. Is this possible? If so, how? If not, is there any other way to screen user registrations? Thank you very much. Gonçalo Luiz