In addition I would see the possibility to auto-respond to staged users that created new posts via email in categories that have email-in activated.
That way they would made knowledgeable of the fact that they are not writing to a mailing list, nor to an email inbox, and could be made aware of the fact that they are in fact interacting with a web-based communication platform.
Oftentimes our users do not know how they can interact with the platform, as it never actively announces itself to them.
This would also make way for helpdesk use cases, in which users hand in tickets.