On 14 Feb 2021, at 10:09, Dave Crocker wrote:
On 2/12/2021 9:03 AM, Pete Resnick wrote:
The examples show Delivered-To: next to the last Received: field,
which implies that Return-Path: is going to get pre-pended after the
Delivered-To: field. If in practice they can appear in either order
(which seems perfectly plausible), that seems like a reasonable thing
to mention. If in practice they always appear in a particular order
(which also seems plausible) and some entity later reading the
message relies on that order (which doesn't seem like a great idea,
but weirder things have happened), that seems like an important thing
to say. Either way, setting expectations seems good.
It's always dangerous to attempt at deriving normative requirements
from examples, of course.
The current text just says to add Delivered-To: to the top and it says
what actor is to do this. I think that has all of what is required
about the field itself.
RFC 5321 (Section 4.1.1.4) has similar detail, in its 5th paragraph.
Guessing at a requirement about the combination of the fields goes
quite a bit beyond either of the specifications.
One could imagine a usage document discussing this, but there does not
seem to be a benefit in creating a constraint about their combination
in this specification.
To the contrary: I am perfectly happy if there is no defined order or
constraint on the order, but I do think it's worth saying that they MAY
appear in either order (i.e., no implementation should ever act on the
order that they happen to appear in).
pr
--
Pete Resnick https://www.episteme.net/
All connections to the world are tenuous at best
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