Re: [ietf-smtp] homework, not an experiment, draft-crocker-email-deliver

> On 6 Aug 2021, at 2:37 pm, Dave Crocker <dhc(_at_)dcrocker(_dot_)net> wrote:
>
> Please explain how the current delivered-to draft does not satisfy these uses 
> with a single field.
If an MUA wants to learn the envelope recipient address to which the
message was sent (by the immediate upstream MUA or relay) then Delivered-To
is not the right header for that.  That's why Exim has Envelope-To, while
Postfix has "X-Original-To:", both of which are intended for consumption by
tools like fetchmail.

My response was to the question of why there are two headers when ostensibly
one would do.  I explained why in fact one is not sufficient, because they
serve different purposes and carry semantically different and often
distinct payloads.

The draft as written does not preclude the present use of Delivered-To, but
its "Experimental" status still makes no sense to me, and to the extent that
it indirectly implies any new semantics for this header (beyond internal
consumption by the generation MTA should the message come back around), then
such semantics cannot be relied on.

If no new semantic meaning is implied, what is the purpose of the "experiment"?

-- 
        Viktor.

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