On the other hand, there is a general rule that email format and user-user
(i.e. UA-UA, i.e, P2-level) work in the IETF might want to treat as
a formal requirement: Internet email travels over a wide variety of
transport and electronic mail protocols and is not limited to SMTP or
its derivatives. Hence, IETF development of message formats should
explicitly and always consider issues in moving objects through Internet
email gateways.
My experience editing the email section of the Host Requirements RFC-1123
leads me to give a heart-felt second to this motion.
Bob Braden