@lbutlr wrote:
> On 23 Nov 2020, at 15:27, Jaroslaw Rafa <r...@rafa.eu.org> wrote:
> > Dnia 23.11.2020 o godz. 11:49:39 D'Arcy Cain pisze:
> >>
> >> If someone replies to a mailing list and copies the sender then that
> >> person gets two copies. The above recipe avoids that.
>
> > Moreover, it breaks the continuity of threads on mailing lists, because it's
> > unpredictable which copy will arrive first, and if only the direct copy is
> > left, the reply will go only to the sender and not to the mailing list. Thus
> > some messages are missing from lists.
>
> This is not accurate. First, the direct message almost certainly
> arrives first. Second of all, that message still has headers
> indicating it was sent to the mailing list.
That is not accurate. The direct message never went through the
mailing list. The direct copy is missing the mailing list headers.
For this list the direct copy is missing these headers.
Sender: owner-postfix-us...@postfix.org
Precedence: bulk
List-Id: Postfix users <postfix-users@postfix.org>
List-Post: <mailto:postfix-users@postfix.org>
List-Help: <http://www.postfix.org/lists.html>
List-Unsubscribe: <mailto:majord...@postfix.org>
List-Subscribe: <mailto:majord...@postfix.org>
The most important of those are List-Id and List-Post without which
the message will not be filed correctly and most mailers will not be
able to list reply correctly. This puts the onus upon the receiver to
manually take corrective action with the message. That is something
that I and probably most readers of this list can do. But for most
random people today they do not understand email and most people today
do not have the skill to do this correctly. For them it is simply
completely broken.
> >> People also send to every alias that someone has. Example,
> >> billing@, admin@, support@, joe@, etc.
>
> > But it's usually one message with multiple recipients, and if all these
> > recipients "resolve" to the same final destination, the receiving MTA
> > usually avoids creating duplicates. At least that was always the case for me
> > as the recipient, no matter if I was using sendmail, Exim or Postfix for my
> > mail.
>
> We are talking about duplicated messages with the same
> message-id. That is one message with multiple recipients. If they
> were separate messages, they would have unique message-id headers.
That is not accurate. A single message to multiple recipients will
have one Message-Id. If you receive it by being the target of some of
those multiple recipients then you will receive multiple copies of the
message and all of the copies will have the same Message-Id.
Bob
