WebGUI is not supposed to reveal users' email addresses if they have marked their email as private in their User Profile (or if their profile as a whole is marked private).
Currently, if a user posts a message to a Message Board forum, everyone who is subscribed to the forum will be sent an email "from" the user, thus revealing the user's email addresss, regardless of the privacy settings the user has chosen.
I appreciate that this behaviour makes sense for a message board that is being used as a mailing list, but users probably won't appreciate their email being exposed if they post directly through the website.
Perhaps the from address should be set to a generic site address if the user has marked their email or profile as private?
Patrick