@mcwumbly though it sounds like groups/private messages feature, IMHO it is a perfect fit for categories. If we enable private messages it is enabled for all. handling with categories provide granular security. again IMHO it is the simplest way to achieve the required result for all the below stated usecases
- to contact list of moderators / admins without private message
- helpdesk for customers in SAAS / any organization
- talk to your CEO / ombudsman kind of scenarios for internal usage in orgs
- for personalized training / q & a among introvert audience.
I would change my topic title to be more generic.