Why not go a step further, and allow people to
specifically permit which users can contact them by e-mail? Anyone else can contact them
on their talkpage, the preferred method of communication in any case.
I, too, give a big +1 to this specifically and the concept in general.
Admins already have a slight version of this ability in the “prevent this user from
sending email” option under the block menu. I must admit that in my more active days with
the mop I have found it quite useful to add “without right of correspondence” (dark
historical associations notwithstanding) to the block message in the case of some users.
Daniel Case