[Mailman-Users] cause of bounces

[Mark Sapiro]

On 10/18/2017 09:31 AM, Grant Taylor via Mailman-Users wrote:
> 
> Um....  My interpretation of 6854 § 1 and § 4 makes me think that an
> empty group list is perfectly acceptable.  Further, the group list can
> be non-empty and contain the lists posting address.


True, but in either case it still does not represent the "author" of the
message.


> I would rather do something like the following so that users could reply
> to the message.  (It would also avoid potential MUA issues as indicated
> by RFC 6854.)
> 
> I would think that it would be acceptable to use a From "group address"
> that is the mailing list.  I.e.
> 
>    From: Mailman Users:mailman-users at python.org;
> 
> Possibly even something like the following:
> 
>    From:  Grant via Mailman Users:mailman-users at python.org;
> 
> Arguably, this is conceptually very similar to what has become the
> defacto method to deal with DMARC today by munging the From:
> 
>    From:  Grant via Mailman Users <mailman-users at python.org>
> 
> The difference is that RFC 6854 codifies that there are times to alter
> the from.  -  At least that's how I'm interpreting this.


That's where you are wrong. All RFC 6854 does is allow the "group"
syntax to be used as the content of the From: header. It does not change
the RFC 5322 at al requirement that the From: header represent the
author(s) of the message.


> Further, if you believe the fact that the outbound message is indeed a
> completely new message (as I do) then it's completely legit to set the
> from to what ever you want.  ():-)


This is the crux of our disagreement. The outbound message is still the
original author's message, albeit slightly altered by subject prefixing,
content filtering and/or other transformations to conform with list
policies. I don't agree that it is a completely new message. I think it
is still the original message with only technical and formatting changes.


>> That type of forwarding is exactly what is done by Mailman's DMARC Wrap
>> Message action and that is the reason that action exists. Because in
>> that case the list message is RFC 5322 compliant. However many MUAs,
>> particularly mobile apps, have difficulty rendering such a message in a
>> good way, so Wrap Message isn't always the best option.
> It sounds like you're talking about message/rfc822 message attachments.
> -  That is a viable option.
> 
> However I see no reason that you can't take the body copy from the
> incoming email and use it directly in the new outgoing email.  No need
> to message/rfc822 wrap (or other digest like raping) the outgoing message.


The difference is wrapping the message preserves the original message's
headers (particularly From:) and makes it the content of another message
which says essentially "here's the message the list received". That
outer message can be From: the list and still be standards compliant.

However, if you are just sending the body of the original message From:
the list, according to RFC 5322 et al, you are saying the list is the
author of that message body. This is not true and is why I say the
message is not compliant with RFC 5322 et al.

Granted, all things considered, this is what most of us choose to do.
I'm not saying this shouldn't be done. It is something we are forced to
do because certain freemail providers choose to publish DMARC p=reject
policies contrary to the original intent of DMARC, but all I'm saying is
we should not forget that when we do this, we are sending messages that
are not strictly standards compliant.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan