@neil @geoffl @dan @bloor What we need is an activity pub gateway protocol that uses TCP port 25 with full SMTP headers so that in all technical ways it is "email" and so exempt.
I think Neil's point makes sense - the operator of the instance is the operator of the service, and they only have one user, so it cannot be a user to user service. It is user to fediverse or fediverse to user, not user to user.