With this plugin you may disallow specific member, who has less than X content items, to start private conversations. They can reply or view the messages list, but can't create them.
- enable/disable whole plugin,
- choose affected member groups,
- set minimum content number to let members start new private conversations,
- you will be able to bypass the limit and let specific members to start new conversations,
- you will be able to force block for creating new conversations per specific members too.