About mail messages and replies (was: Motion P1788/M0034.01 Notation:NO)
On 2012-06-14 18:22:07 -0400, Michel Hack wrote:
> I used to think that the Subject: tag would be enough to maintain a
> thread, but apparently that is not sufficient for some mail handlers.
The subject is not sufficient because
1. with the subject only, the reader can't see the message you are
replying to (and the other ancestors, if one needs to track a
whole discussion);
2. several unrelated discussions may have the same subject;
3. the subject may sometimes change a bit (or completely). The
subject may change to reflect a change in the discussion, but
one usually still wants the references to the older messages
for the context (and because the discussion has generally
started to change several messages before).
Conversely, to start a completely new discussion, it is bad to reply
to some arbitrary message even if the subject is changed, because the
new message will contain a reference to the old discussion.
> Actually, there is a lot to be said for NOT depending on blind copying
> of subject lines. The one we've been repeating here looks like a vote,
> but that was just the spark of a discussion. So having an independent
> thread id would be nice, but I'm not sure if there is a Mime format for
> thread identification.
Thread identification is done via "References:" and "In-Reply-To:"
(ideally, the initial Message-ID should be kept, even when trimming
references if it becomes too large). This has existed even before
MIME.
> I certainly don't want to include the entire e-mail chain -- especially
> not backwards, as most mail handlers seem to present it. In any case,
> the receiving mail handler should replace them by cross-references, but
> given the lack of standards for presenting the history, this is difficult
> to automate. I do that for my incoming mail, but it is partially manual
> because I have not been able to figure out a reliable way to program it.
> (I do have helper macros to find the references.)
How "References:" and "In-Reply-To:" have to be handled by mail
software is described in RFC's (currently, RFC 5322[*]).
[*] http://www.faqs.org/rfcs/rfc5322.html
--
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)