On 6/19/2020 12:02 PM, Pete Resnick wrote:
On 19 Jun 2020, at 13:38, Dave Crocker wrote:
The description of what a Mediator might do is not incompatible with
also viewing it as having characteristics of a publisher:
### [5.3](<https://tools.ietf.org/html/rfc5598#section-5.3>).
Mailing Lists
...
In addition to sending the new message to a potentially large
number
of new Recipients, the Mailing List can modify content, for
example,
by deleting attachments, converting the format, and adding list-
specific comments.
Fair enough, but as you mention below, in the case of the common
mailing list, the intent is simply to redistribute the message with
minimal change (hence the retention of the Message-ID: and the From:).
While, yes, that's the goal of some and probably most lists, that isn't
quite what I said.
Please re-read my text, which notably did not contain the word 'minimal'
and frankly had a different focus. That focus doesn't exclude
minimality, but it wasn't the point.
That said, I do disagree with the reasoning given with regard to why
5321.MailFrom has changed: It's not because of the authorship, but
rather because it is responsible for the submission onto the network,
just as the ReSender is in 5.2.
I did not anything about MailFrom, or for that matter anything about any
field with an identifier.
I'm guessing that your reference is to the fact that a mailing list
service might put its own address into the MailFrom, so it gets handling
error messages? That issue and behavior predates DMARC by a lot.
Probably two decades. Maybe more.
Note that in terms of email transport, it is posting a new message.
Strictly in terms of transport, yes. But in terms of the layer above
(the 5322 layer), it is usually the same message; see the second Note:
in RFC 5322 section 3.6.4:
Note: There are many instances when messages are "changed", but
those changes do not constitute a new instantiation of that
message,
Except that there are many instances when messages might be changed that
DO constitute a new instantiation of that message, and 5322 gives no
guidance about what determine one versus the other.
None of which is relevant to the point that a mailing list service has
its own agency and is free to do what it wishes to and with the messages
it is re-posting. That most seek to preserve essentially all of the
author's text is fine, but whether and how much is more of a 'business'
decision than a technical one.
Mediators really have complete freedom to do whatever they want. If
describing the full range of what a publisher might do, it would
cover the same range.
Well, "complete freedom" in the sense that no Internet police prevent
such actions.
I didn't mean anything so nit-picky. I mean that they are providing a
value-added service to users and have their own agency to decide what
that service looks like. If they want to do assorted message
modifications that are substantial, and if users of the service like the
nature of those modification, the service is free to do them. There is
no specifications that dictate or even suggest, what one of the services
must, or even should, do. So your reference to Internet police is
ironic, because there is nothing to guide enforcement.
But for most mediators, large substantive (for interesting definitions
of "substantive") changes are outside of the scope of their
definitions, and would probably invite someone to say, "That's not
being a mediator." Certainly that would happen in the case of an alias
or a resender.
If there is a specification that would move such a declaration out of
people's personal opinions and into objective, technical assessment, I
apologize that I don't know what it is.
But typical mediators are trying to maintain a sense and ability for
the original author and the final recipient to experience an
end-to-end message exchange.
Yep. That's the point I was trying to make.
Except you seem to be pressing this as essentially a requirement they
have whereas I'm pressing it as a business decision, not something
inherent in the nature of mailing list behavior.
The degree to which the mediator asserts itself more visibly to the
recipient is probably the degree to which it looks more like a
publisher and less like a simple relaying service.
And eventually, I would contend, less like a mediator.
I probably wouldn't like it either, but we don't have objective criteria
for accurately and reliably applying or withholding the term, do we?
d/
--
Dave Crocker
Brandenburg InternetWorking
bbiw.net
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