Second, nobody has answered the challenge of coming up with an example
of 8->7 bit conversion at an MTA not intimately linked to the sending or
receiving UA. Any such example in a pure Internet mail context would
be quite artificial.
Oh, well. What about uunet MX-ing? uunet receives a lot of mail for its
uucp customers. And the uucp maps! Internet mail for these sites
may be transfered to one site on the internet and then forwarded thru
maybe lots of links to its final destination. Nobody knows if the mail
will enter some kind of internet again on its way, eg. a huge
corporate network. You may say that this is gatewaying issues,
but anyway it will require 8-to-7 bit transformations, that it would
be very convenient if this was well specified.
But the key point is that it is a gateway; rules for MTAs do not apply.
Ned