Hi Dave --
I have to key on your last sentence, and say that for me, a gateway is
any entiry that does what is described in this sentance, for any
reason at any time. You say:
The gateway performs format and/or sematic (content) conversions on
messages, to make them palatable to the receiving email service.
I am greatly bothered by your limiting gateways to cases where it does
this for a limited set of reasons.
How now do we deal with all those other "do-gooder" reasons that
Nathaniel has raised, like "conservation of anticipated downstream
bandwidth limitations" to justify conversion to JPEG.
What does motivation have to do with it?
What has everything to do with it as I see things is whether or not
layer-n lays a hand on and transforms any part of layer-n+1 protocol
data units or service elements. That defines a gateway, pure and
simple. I must never be done without some kind of layer-n+1
authroization, or we grossly weaken our entire abstract model.
It is very dangerous to say things that can be intereted to mean "It
was not a gateway action because my motives were pure as the new
driven snow!, even though it woudl have been a gateway function if my
motives had been to transform it for another environment".
I trust that you se emy point...\Stef