Re: Rmail does not mark buffer modified when unread message is shown

[Eli Zaretskii]

> From: Göktuğ Kayaalp <self@gkayaalp.com>
> Cc: help-gnu-emacs@gnu.org
> Date: Mon, 07 May 2018 01:17:43 +0300
> 
> On 2018-05-06 05:41 +03, Eli Zaretskii <eliz@gnu.org> wrote:
> > If you start Emacs as "emacs -Q" and then invoke "C-u M-x rmail RET"
> > on an mbox file, do the problems go away?  For this experiment, please
> > try an mbox file that wasn't converted as you described, but came from
> > somewhere else, for example from the archives of this list.
> 
> I tried this, the buffer modified flag is not flipped and thus ‘s’ and
> ‘C-x C-s’ don't work, the latter causing the message «(No changes need
> to be saved)» to be displayed.

Yes, I remember now: this is a feature.  Just reading a message
doesn't mark the inbox buffer modified, although it does remove the
"unseen" attribute from the message (you can see that, e.g., in the
Summary buffer, where unseen messages have their summary line
highlighted).

The reasons for this behavior are largely historical now: they have to
do with the move from Babyl to mbox format for storing messages in
files.  We could change this behavior, but I guess at this point it's
burnt into too many muscle memories.  In practice, this never presents
a problem, because it's a rare case that you read your new mail and
don't delete or file away even a single message.  The latter two
operations do mark the inbox buffer modified.  So to wqork around
this, just do 'd', then 'u', and you will be able to save your inbox.