Re: [ietf-smtp] Who should set the Sender: header field?

Valdis Kl ē tnieks <valdis.kletnieks@vt.edu> Wed, 15 December 2021 05:16 UTC

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To: Alessandro Vesely <vesely@tana.it>
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Date: Wed, 15 Dec 2021 00:15:50 -0500
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Subject: Re: [ietf-smtp] Who should set the Sender: header field?
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On Tue, 14 Dec 2021 10:27:20 +0100, Alessandro Vesely said:

> Of course, I meant only in case the user added multiple mailboxes to From:.
> RFC 5322 requires that a Sender: field be there in such cases.

I wonder how many of the 800 pound gorillas in the email world still allow
multiple addresses in the From: field - any proposal for weird headers that get
rejected by either Google or Microsoft (rather than silently ignored and passed
along) is de facto DOA, no matter what the de jure status is.

No, I'm not thrilled by this situation, but here we are anyhow.

Which gets me wondering - what *other* "still officially legal but not usable
except in small private conclaves" features are still out there? I know
that nmh/exmh dropped message/partial support because nobody seems
to be using it in the wild...