Subject: [ietf-822] References: none

From: Johnathan Galton <[email-masked]>
Date: Tue, 30 Apr 2019 14:51:18 -0700

Hello-

Is there any standard way for a mail client to tell recipient that "I'm
aware of References and In-Reply-To headers but this email is not a reply
or related to another email"?  So that recipient's mail client could
authoritatively know that this email doesn't "thread" with anything else;
as I don't think recipient can be entirely safe in assuming that the lack
of a References/In-Reply-To headers will always mean that it's a new thread
vs the possibility that the sender isn't aware of/properly using those
headers in the rfc2822 sense[1]?  (e.g. maybe some explicit signal like
`References: none`)?

[1]  Gmail, for example, still falls back to threading by subject
<https://webapps.stackexchange.com/questions/965/how-does-gmail-decide-to-thread-email-messages>
when
References/In-Reply-To are absent.

Thanks,

---

From: "John Levine" <[email-masked]>
Date: 30 Apr 2019 22:14:23 -0400

In article <[email-masked]> you write:
>or related to another email"?

The short answer is no.

It might be interesting to put the message's own message-id in the
references and reply-to header and see what happens.