Make Message more RFC compliant

Make Message more RFC compliant

[Lars Ingebrigtsen]

There are recentish (I mean, only a few years old) RFCs that now specify
that From addresses on the form

  From: larsi@gnus.org (Lars Ingebrigtsen)

SHOULD not be generated, because they create problems for some
recipients (*cough* Microsoft Mail *cough*):

Only this form is allowed now:

  From: Lars Ingebrigtsen <larsi@gnus.org>

Michael Stapelberg <stapelberg@debian.org> writes:

>>    Note: Some legacy implementations used the simple form where the
>>    addr-spec appears without the angle brackets, but included the name
>>    of the recipient in parentheses as a comment following the addr-spec.
>>    Since the meaning of the information in a comment is unspecified,
>>    implementations SHOULD use the full name-addr form of the mailbox,
>>    instead of the legacy form, to specify the display name associated
>>    with a mailbox.

So:

The RFC says SHOULD, so Message shouldn't have an easy way to generate
From headers that deviate from the `angles' style.

So I propose to remove the code that reacts to `message-from-style'
(i.e., always generate `angles' From headers), and mark
`message-from-style' as obsolete and note in the doc string that it's no
longer used.

Any objections?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: Make Message more RFC compliant

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Fri, 13 Apr 2018 23:27:17 +0200
> 
> >>    Note: Some legacy implementations used the simple form where the
> >>    addr-spec appears without the angle brackets, but included the name
> >>    of the recipient in parentheses as a comment following the addr-spec.
> >>    Since the meaning of the information in a comment is unspecified,
> >>    implementations SHOULD use the full name-addr form of the mailbox,
> >>    instead of the legacy form, to specify the display name associated
> >>    with a mailbox.
> 
> So:
> 
> The RFC says SHOULD, so Message shouldn't have an easy way to generate
> >From headers that deviate from the `angles' style.
> 
> So I propose to remove the code that reacts to `message-from-style'
> (i.e., always generate `angles' From headers), and mark
> `message-from-style' as obsolete and note in the doc string that it's no
> longer used.
> 
> Any objections?

I don't understand why we need to remove the support code.  Making the
variable obsolete is OK, but if there's someone out there whose bad
habits die hard, or who needs to communicate with some weirdo mail
software that requires this obsolete format, why not let them do it?

Or am I missing something?

Re: Make Message more RFC compliant

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> I don't understand why we need to remove the support code.  Making the
> variable obsolete is OK, but if there's someone out there whose bad
> habits die hard, or who needs to communicate with some weirdo mail
> software that requires this obsolete format, why not let them do it?
>
> Or am I missing something?

Well, sending emails with the old format is now apparently in violation
("SHOULD") of the relevant RFCs, and I think Emacs should be
standards-compliant when talking to other systems, and not generate
invalid emails.

If a user really really needs to send an invalid email, that's also easy
enough without Emacs having direct support for it: Just type in the From
header in the Message buffer, and Message will send out whatever you ask
it to.

We don't control (and don't want to control) what people are allowed to
do, but we can control what we generate.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: Make Message more RFC compliant

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: emacs-devel@gnu.org
> Date: Sat, 14 Apr 2018 15:04:10 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I don't understand why we need to remove the support code.  Making the
> > variable obsolete is OK, but if there's someone out there whose bad
> > habits die hard, or who needs to communicate with some weirdo mail
> > software that requires this obsolete format, why not let them do it?
> >
> > Or am I missing something?
> 
> Well, sending emails with the old format is now apparently in violation
> ("SHOULD") of the relevant RFCs, and I think Emacs should be
> standards-compliant when talking to other systems, and not generate
> invalid emails.

Sorry, I'm not convinced.  If the user insists on using deprecated
features, I see no reason to prevent them just because some RFC says
SHOULD.  Our defaults should not generate invalid or frowned-upon
headers, but that and the obsolescence of the variable is more than
enough for us to be OK with the standards.

Re: Make Message more RFC compliant

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> Sorry, I'm not convinced.  If the user insists on using deprecated
> features, I see no reason to prevent them just because some RFC says
> SHOULD.  Our defaults should not generate invalid or frowned-upon
> headers, but that and the obsolescence of the variable is more than
> enough for us to be OK with the standards.

Ok, I've now changed the default of the -from-style variables to
`angles' and marked them as obsolete.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no