Re: [PATCH] wip: Add forward-message-refs function.

On Thu, Aug 27, 2026 at 10:58 +0800, Kevin J. McCarthy wrote:

>This reuses the existing Mutt functions to set references, which means
>they are like reply references: the full list.  It clears out the
>In-Reply-To header afterwards, because I personally feel like that
>header is a step too far for a "forward".

So In-Reply-To: is for a reply, but References: is for something else?

Apparently that was true in 1982, when RFC 822[1] was published -- but 
that something else was not defined. Maybe it hadn't been invented yet.

Here's everything that RFC 822 says about those two headers:

4.6.2.  IN-REPLY-TO

             The contents of this field identify  previous  correspon-
        dence  which this message answers.  Note that if message iden-
        tifiers are used in this  field,  they  must  use  the  msg-id
        specification format.

4.6.3.  REFERENCES

             The contents of this field identify other  correspondence
        which  this message references.  Note that if message identif-
        iers are used, they must use the msg-id specification format.

By 2001, when RFC 2822[2] was published, References: had evolved to:

      The "In-Reply-To:" and "References:" fields are used when
      creating a reply to a message....the "References:" field may
      be used to identify a "thread" of conversation."

In 2008, RFC 5322[3] still had exactly that paragraph from RFC 2822.

So for at least the last 25 years, and probably since Mutt came into 
existence, References: has been a path through a thread of replies. Far 
as I know, nothing else was ever implemented.

-------------

[1] <https://www.rfc-editor.org/info/rfc822/#section-4.6>
[2] <https://www.rfc-editor.org/info/rfc2822/#section-3.6.4>
[3] <https://www.rfc-editor.org/info/rfc5322/#section-3.6.4>