This is a feature request for a new socialprofile permission (boardblock) so that users can block others from leaving them public or private messages on their userBoard, this would reduce the resources of admins to mediate these such conflicts. Obviously this shouldn't prevent admins from leaving messages or allow submitting a complaint (restricted special page?).This requires additional SQL tables (boardblocked, complaints) and special pages (complaints, userBoardBlock).

While WMF is working on a prototype to allow ignoring user messages/notifications, unsure this would extend to existing extensions. if it does not and If no one is interested in expanding for this, I would be interested in adding this feature.