BuddyPress Private Message Rate Limiter GPL Overview:

The BuddyPress Private Message Rate Limiter plugin permits you to restrict customers from sending massive numbers of messages and flooding different customers on your BuddyPress-based social network. The first-rate use case for this plugin is to give up spammers from flooding your user’s non-public messages.

• Site Admin can restrict solely the new messages (best ideal for unsolicited mail prevention)
• Site Admins can restrict the new messages and replies each ( We suggest the 1st alternative to keep away from spammers but let normal customers continue)
• Site Admin can set the length of time for which the restriction will follow