@smallcircles @steve I also think that providing some more feedback in the response to a post to `inbox` or `outbox`. When a server gets an `Accept` for an `Invite` to an `Event`, for example, it might be able to give a response that says, "I understand this and will implement its side-effects", or "I'm going to distribute this, but I don't know what it means, so don't expect any side-effects", or "I'm not going to even distribute it."