Re: Rmail: toggle between summary and message buffers

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 22 Jun 2019 10:04:16 +0200
> From: Xavier Maillard <xavier@maillard.im>
> Cc: help-gnu-emacs@gnu.org
> 
> > > Don't use "C-c C-c".  Use "C-c C-s" instead, and have a separate frame
> > > for the *mail* buffer where you compose and send email.  Then Emacs
> > > will not mess up your windows in the Rmail frame.
> > 
> > Btw, a nice side effect of this arrangement is that the next 'm' or
> > 'r' will reuse the frame showing the *mail* buffer, so just let that
> > frame hang around, to be used for composing and sending email
> > throughout the entire session, with no need to switch to any buffer in
> > your other frames.
> 
> I will test this but here it does not seem to select the right frame.

I think you also need to set rmail-mail-new-frame to a non-nil value.
With that, the first time you reply to an email from Rmail, it will
create a new frame for the outgoing email, if one doesn't already
exist.

You will also need to set message-generate-new-buffers to the value
'standard', so that the name of the buffer where you compose email is
fixed (and thus it could be reused for subsequent email messages).
Alternatively, do this:

  (setq mail-user-agent 'sendmail-user-agent)

which will ensure the outgoing email buffer is always named "*mail*".

Sorry, forgot to tell about all that (this is setup I've done many
years ago).