Resources
https://github.com/buddypress/BuddyPress/blob/master/src/bp-messages/bp-messages-functions.php
Functions
Create a new message
messages_new_message()
Send a notice
messages_send_notice()
Delete all message threads for a user
messages_delete_thread()
Does user have access to a thread
messages_check_thread_access()
Mark a thread as read
messages_mark_thread_read()
Mark a thread as unread
messages_mark_thread_unread()
Get unread messages count for user
messages_get_unread_count()
Is user the sender of a message
messages_is_user_sender()
Feel free to comment if you can add help to this page or point out issues and solutions you have found. I do not provide support on this site, if you need help with a problem head over to stack overflow.