Re: APOP support in movemail

[Simon Josefsson <jas@extundo.com>]

"Eli Zaretskii" <eliz@elta.co.il> writes:

>> From: Richard Stallman <rms@gnu.org>
>> Date: Fri, 07 Nov 2003 21:16:04 -0500
>> 
>> I think it is useful at this point for me to restate the GNU project
>> policy that support for non-free operating systems such as Windows is
>> a secondary priority.  We will not make major design decisions based
>> on what does or does not suit Windows.
>
> I'm with you on that, but this policy is not really relevant to this
> discussion: APOP is not a Windows-only feature, and neither does it
> favor Windows in any way.  GNU and Unix users will need APOP in
> movemail as long as we continue using movemail as the primary means of
> fetching mail from POP3 servers into Emacs.

Continuing to support movemail in Emacs only because it works on
Windows, even though the best long-term solution may be to choice
something else (that might not work immediately for Windows), would be
relevant, I think.  The 'something else' solution might be to move
'movemail' into GNU MailUtils and have it use the MailUtils POP3
library (which already support APOP and STARTTLS, judging from a quick
browse in the MailUtils CVS).

Consider also the question of adding support for STARTTLS or SASL
(e.g., to support Kerberos 5 via GSSAPI) to movemail as well.  Adding
these features when movemail is part of Emacs would make Emacs depend
directly on the MailUtils library, GNUTLS and/or GNU SASL.  I have
received several requests for this feature for SMTP, I suspect POP3
users will start to request it as well.

The ideal solution would, IMHO, be to have only interface in Emacs to
access POP3 and make it supports all features users wants.  Right now,
I believe there are too many solutions, all with different kind of
feature sets and bugs.  It is difficult to write good manuals or
answer user questions for this kind of situation.

  - movemail.  Works on Windows.  No APOP/STARTTLS/SASL.
  - pop3.el.  Works on Windows (?).  Support APOP.  No STARTTLS/SASL.
  - epop3 (not part of Emacs).  Works on Windows (?).  Support APOP, and
    "leave-mail-on-server" feature frequently requested.
  - fetchmail (not part of Emacs).  Works on Windows (?).  Supports
    GSSAPI/Kerberos.

As for the solution, I think I would vote for extending pop3.el with
e.g. APOP functionality, and have it fall back to an external
application (e.g., 'gsasl') instead of `open-network-stream', for
those authentication systems that can't be implemented natively in
elisp (STARTTLS and certain SASL mechanisms).  Most of this code has
already been written, but it would have to be adapted for pop3.el.

The 'movemail' application could remain in Emacs, but it would only be
responsible for moving mail from /var/spool/mail.  (Although is it
still the case that the special file locking movemail does cannot be
implemented in elisp?)

An alternative is to move 'movemail' to MailUtils, and make it use the
MailUtils library (to get you the APOP support, and possibly other
features, such as UIDL which I believe is required for
"leave-mail-on-server").

A combination is possible, e.g. extend pop3.el as described, _and_
move 'movemail' to MailUtils and extend it to support APOP.  This
might be required for backwards compatibility.

Of course, simply adding APOP support to movemail in Emacs could be
done now, pending the above migration that will bring users support
for STARTTLS, SASL, UIDL etc.