On Mon, Oct 18, 2010 at 13:37, Carlos E. R. wrote:
This could be handled with a web form. You fill out some data and a private message is sent to the person, without telling the sender the address. If the destinatary wants to answer, he can. A requirement could be to log in first.
This is already possible (with a form) in any MediaWiki based Wiki (including not revealing the user email address)... but only if the user has not turned off the "Enable e-mail from other users" option in their user preferences (allows other users to click an "E-mail this user" link from the User:username page). If they've disabled this option in their user preferences, then there is no way other than the SQL select to find/contact the person.