quan_flo

If there is a user (or a bot) that signed up at your site this user can start to send messages to every other user. 
I had some negative experiences with this and so I wrote a module that should help to block such a spam.
Buddypress Messages Spam Blocker introduces some restrictions to your users:
<ul>
<li>New users can send messages only 24h after their registration, so you’ll have time if bot registrations have to be removed manually (modify this value using filter ‘buddypress_messages_spamblocker_newMembersWaitingPeriod’)</li>
</ul>
Their are also some more restrictions for mass mailings (mails that are sent to “friends” of the contact list are not included in this calculation):
<ul>
<li>Users can send 6 messages maximum in 5 minutes (modify this value using filter ‘buddypress_messages_spamblocker_5m’)</li>
<li>Users can send 10 messages maximum in 10 minutes (modify this value using filter ‘buddypress_messages_spamblocker_10m’)</li>
<li>Users can send 20 messages maximum in 30 minutes (modify this value using filter ‘buddypress_messages_spamblocker_30m’)</li>
<li>Users can send 30 messages maximum in 60 minutes (modify this value using filter ‘buddypress_messages_spamblocker_60m’)</li>
<li>Users can send 35 messages maximum in 12 hours (modify this value using filter ‘buddypress_messages_spamblocker_12h’)</li>
<li>Users can send 45 messages maximum in 24 hours (modify this value using filter ‘buddypress_messages_spamblocker_24h’)</li>
<li>Users can send 50 messages maximum in 48 hours (modify this value using filter ‘buddypress_messages_spamblocker_48h’)</li>
</ul>
Users with the capability “edit_users” (admins etc.) have no restrictions for outgoing messages
Install, activate, and it will work.
More about me and my plugins
Since the year 1999 I do administration, customizing and programming for several forums, communities and social networks. In the year 2013 I switched from another PHP framework to WordPress. 
Because not all plugins I’d like to have exist already I wrote some own plugins and I think I’ll continue to do so.
If you have the scope at forums or social networks my other modules might also be interesting for you. <a href="https://wordpress.org/plugins/search.php?q=quan_flo" title="ifs-net / quan_flo WordPress Plugins" rel="ugc">Just take a look at my WordPress Profile to see all my Plugins.</a> Use them and if my work helps you to save time, earn money or just makes you happy feel free to donate – Thanks. The donation link can be found at the right sidebar next to this text.

Buddypress Messages Spam Blocker

This plugin will block mass mailing for the buddypress messaging system

Piotr Pesta

<a href="https://github.com/Pantsoffski/Author-Chat-Plugin" rel="nofollow ugc">Author Chat</a> is an internal chat that let your authors (users with access to admin panel) to chat with each other. It is easy to use. All chat data is stored in database. You can also configure how many days chat history should be stored in database, change the interval time for the verification of new messages, show or hide our name in the messages and many more.
Author Chat now supports private chat/chat rooms.
You can also download Author Chat client for Android, and run chat on your smartphone. App is available here: <a href="https://play.google.com/store/apps/details?id=pl.ordin.authorchat" rel="nofollow ugc">Google Play</a>
If you wish to translate plugin, just add your translation file to /lang/ folder.
<h3>Using 3rd party service</h3>
Please note that this plugin is relying on a 3rd party service, which is the Google Firebase Cloud Messaging service (FCM) and your data is being sent through their servers via HTTP API (https://fcm.googleapis.com/fcm/send). This is very legal to use the Google Firebase Cloud Messaging service (FCM), based on their terms and conditions https://firebase.google.com/terms/.

Author Chat

Author Chat is an internal chat that let your authors (users with access to dashboard) to chat with each other. It is easy to use and supports private …

Buddypress Messages Spam Blocker vs Author Chat