One of the main challenges of hosting your own BuddyPress social network is making it easy for members to communicate with one another. BuddyPress does not include mass messaging as part of the default download, but you can now get it with the new Mass Messaging in BuddyPress plugin.
This plugin gives you the ability to offer mass messaging for:
Members of Groups
Members of Events (EventPress)
After installing the plugin, you’ll get a tab for mass messaging in the messaging section as well as a dashboard menu: