BuddyPress Restrict Messages is a useful plugin for sites that wish to control in-site spam to users. It comes with two modes of operation – Admin control and User control, these allow users or site admin to restrict messaging to friends, followers or just to members of the same groups.
This plugin brings BuddyPress post statuses to the front-end, with a simple yet highly customizable user interface supporting Friends Only, Members Only, Group and Follow post statuses. Designed to work with both BuddyPress and BP Post Status, this plugin adds features no other plugin can.