Re: master 42596bd 2/6: Little improvements in rmail.el. Recognize encryped override headers.

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Lars Ingebrigtsen <larsi@gnus.org>,  rms@gnu.org,  emacs-devel@gnu.org
> Date: Wed, 12 May 2021 11:14:47 -0400
> 
> Eli Zaretskii [2021-05-12 16:12:46] wrote:
> > Drew might be a single person, but he tends to flood the Emacs mailing
> > lists with a lot of messages carrying this addition.  Rmail's
> > threading is based on comparing their Subject lines, and Rmail already
> > has quite a few heuristics whose purpose is to clean up the Subject
> > line to that end.  I see nothing wrong with adding one more
> > heuristics; the problem hits me as well.
> 
> But this shouldn't be embedded directly into the code.
> We should have instead a variable specifying those cases (so it can be
> extended/adjusted depending on the cases the users face).

It's an internal implementation detail that no user will ever want to
change, so I see no reason to have a separate variable.  We already
have several strings there hard coded into the function, and I see
nothing wrong with having one more.

If it turns out this addition comes in several variants that are not
expressible as a simple regexp, we will probably make a variable, as
we do with other similar additions.