@renchap I think sending Deletes just to followers is a decent solution, if combined with servers refreshing an actor every time it appears in an Activity or Object. Ie, if some server wants to send a Note to a bunch of recipients the server should refresh the actors, and then notify the user that they're trying to send the Activity to invalid actors for every received Tombstone (or even removing them all together from the recipients list).

@pkreissel