From: Mark Walters <markwalters1009@gmail.com>
To: Eric <eric@deptj.eu>, notmuch@notmuchmail.org
Subject: Re: Breaking a really long thread
In-Reply-To: <c10e501c2baee471cbeeb42aad89a1e966407234-NM@bruno.deptj.eu>
References: <c10e501c2baee471cbeeb42aad89a1e966407234-NM@bruno.deptj.eu>
User-Agent: Notmuch/0.18.1+485~gca076ce (http://notmuchmail.org) Emacs/24.4.1
 (x86_64-pc-linux-gnu)
Date: Mon, 04 Apr 2016 14:00:26 +0100
Message-ID: <87k2kd8r6d.fsf@qmul.ac.uk>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: list

On Mon, 04 Apr 2016, Eric <eric@deptj.eu> wrote:
> On Sat, 02 Apr 2016 06:56:12 -0700, David Mazieres <dm-list-email-notmuch@scs.stanford.edu> wrote:
>> David Bremner <david@tethera.net> writes:
>> 
>>> David Mazieres <dm-list-email-notmuch@scs.stanford.edu> writes:
>>>
>>>> Is there any way to break an existing thread (so as to start over with a
>>>> smaller thread), or otherwise to tweak the threading rules so that a
>>>> particular References header gets ignored.
>>>
>>> Currently there is no way to do this, as threads are "stateless"
>>> i.e. created on the fly by _notmuch_create_thread based only on
>>> immutable mail data.
>> 
>> Thanks.
>> 
>>>> It's annoyingly slow to open
>>>> a thread with 10,000 messages just to read one SMS.  I'm almost tempted
>>>> to mangle the messages on delivery and remove the References header
>>>> before notmuch sees them, but it would be nice to have a cleaner
>>>> solution, as there are other situations in which one might want to
>>>> "reset" a really long thread.
>>>
>>> Like this thread ;).
>> 
>> Oops, sorry for the irrelevant thread inclusion.  I guess emacs adds the
>> References header after a message is sent is sent?  In my setup, the
>> easiest way to post to a mailing list is to reply to an existing message
>> (since I subscribe to each list under a different email address).  I
>> tried to start a new thread by deleting the In-Reply-To and header which
>> was all I saw, but I guess the References header got inserted later...
>
> Neither notmuch emacs nor any other email client has any business
> inserting a References header after the user "presses Send". On a new
> message it shouldn't exist unless inserted manually, and on a reply it
> should come from the replied-to message (and be changed) before you start
> "replying". More likely that (if you didn't miss it) it was not shown
> to you although it existed - that would count as a bug in my opinion
> (I don't use emacs for anything, not even notmuch).

By default the reference header is hidden. It is controlled by
message-hidden-headers which you can customize. (Note notmuch adds
user-agent to this list via notmuch-mua-hidden-header.)

> Actually the message you replied to has no References header, but notmuch
> reply (command line) to it generates both References and In-Reply-To
> (same content). I assume notmuch emacs does the same. I don't believe
> that References should be generated in this situation, its only use
> would be by a threading algorithm that doesn't use In-Reply-To, and I
> would consider that a bug in said algorithm.

That isn't my reading of RFC2822 (section 3.6.4):

   The "References:" field will contain the contents of the parent's
   "References:" field (if any) followed by the contents of the parent's
   "Message-ID:" field (if any).

> Actually I think there should be a "reply as new" option which uses
> the other message but does not add either In-Reply-To or References
> (and does not carry the latter forward if it exists).

That would be possible. If you don't actually want to include the
message itself then "c f" to stash the from, and then pasting that as
the "to" address gets pretty close.

Best wishes

Mark