[MERGE] Add mail-mode GNU Emacs mail package as a mail_client option.

[Vincent Ladeuil]

>>>>> "aaron" == Aaron Bentley <aaron at aaronbentley.com> writes:

    aaron> Vincent Ladeuil wrote:
    aaron> Though I still have doubts about whether we should be
    aaron> supporting two different ways of sending mail via
    aaron> emacs...
    >> 
    >> Look at it that way:
    >> 
    >> We should support several different ways of sending mail from
    >> Ubuntu because there exists several available MUAs.

    aaron> Note that Ubuntu *does* provide a standard way of
    aaron> launching the user's preferred mail client: xdg-email.
    aaron> Windows and Mac also have ways of launching the
    aaron> preferred mail client.

    >> Now replace Ubuntu by emacs.

    aaron> If Emacs is an OS, why doesn't it have such a facility?

Good point. 

But then Xaviers's patch may have to be tweaked: instead of
trying to integrate one set of emacs constraints into bzr,
integrate just a minimal call through xdg-email (or not) and
handle all the emacs related customizations* in emacs itself**.

I never tried to address it myself since I'm perfectly happy with
'bzr send -o <file>' or 'bzr send -o-' and attaching the
resulting file from my MUA (gnus).

    >> And I'm serious :)

    aaron> I've seen lots of people claim that Emacs is a
    aaron> operating system, not an editor.  But this is the
    aaron> first time I've seen an Emacs user admit it.

And proud of it :) It hides most of the underlying OSes quirks,
but behave a little on windows... Go figure, I heard rumors
that Java virtual machines suffers too.

    aaron> Bazaar shouldn't need its own facility.  It has one because:

    aaron> - xdg-utils isn't installed everywhere (62% of Ubuntu
    aaron>   machines have it, according to popcon.ubuntu.com)

Then having a generic emacs ExternalMailClient may be appropriate
(xdg-utils may not be available on OSX nor windows nor Solaris,
etc).

    aaron> - thunderbird is quirky, and supporting it directly
    aaron> seems to work best.

Thanks for implying that emacs is not quirky :-P

More seriously, I can understand the concerns about supporting
every possible MUA in bzr core, but why not providing plugins
then ? We should find the right balance between 'batteries
included' and 'everything and the kitchen sink included'.

Finally another API may be around mailto URLs...

       Vincent

*: emacs version (why require 22.1 ?), rmail or gnus, specific
 ways to add attachment (including inline), required in-buffer
 movements, etc.

**: This will be mentioned on the wiki page*** related to using
  bzr from emacs or included as a .el file in the contrib
  directory.

***: What ? I've still haven't created that one, oh my god...