On Mon 13/Dec/2021 23:07:20 +0100 Dan Mahoney via mailop wrote:
On Dec 13, 2021, at 1:55 PM, Vsevolod Stakhov via mailop <mailop@mailop.org>
wrote:
On 13/12/2021 17:19, Alessandro Vesely via mailop wrote:
Hi,
I assume everybody knows that RFC 5322 allows multiple mailboxes in the From:
field. This feature existed in RFC822 already. I think it is to be used for
those cases where multiple persons are authoring a message, albeit adding the
list of coauthors is usually not done. This message is an example. How many
rejects does it yield?
Gmail reacts like so:
Action: failed
Status: 5.0.0
Remote-MTA: dns; gmail-smtp-in.l.google.com [108.177.119.27]
Diagnostic-Code: smtp; 550-5.7.1 [192.0.2.4 13] Messages with multiple
addresses in From:
550 5.7.1 header are not accepted. do22si22787062ejc.211 - gsmtp
Is it customary to reject messages with multiple addresses in From:? Why?
This is a clear case where RFC is wrong and bogus when one takes into
consideration other Internet standards, for example DMARC or even DKIM. There
is also a clear way to implement the behaviour you've described without such a
violation: just add a Reply-To header with multiple addresses.
Rspamd has a high score rule to penalize messages with multiple from, as I've
seen just spam with multiple from headers in practice like other people in this
mailing list.
Yeah, the university edge-case was one I could think of where for
academic/journalistic reasons both a student and professor would be
co-authoring/co-publishing a thing. (Naming order is distinct enough (and
matters) in that field, but I'll totally admit it's an extreme outlier).
Firmly keeping that there must be one and only one From: field, since From: can
have multiple mailboxes at least since RFC 822, it is easy to see which RFC is
wrong.
Best
Ale
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