Date: Thu, 7 Mar 1996 12:53:53 -0800 (PST)
From: Mark Crispin <MRC@Panda.COM>
Sender: Mark Crispin <mrc@Ikkoku-Kan.Panda.COM>
Subject: Re: Message format document outline
To: John Gardiner Myers <jgm+@CMU.EDU>
Cc: drums@cs.utk.edu
In-Reply-To: <ElDoheS00WBwQvhEU4@andrew.cmu.edu>
Message-Id: <MailManager.826232033.10347.mrc@Ikkoku-Kan.Panda.COM>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; CHARSET=US-ASCII

On Thu,  7 Mar 1996 15:47:38 -0500 (EST), John Gardiner Myers wrote:
> > > These are all illegal per RFC 822 and should continue to be illegal.
> > Where does 822 say this?  I'm pretty sure that I remember an emphatic
> > statement otherwise.
> 822 has no rule or sequence of rules to permit it.

Neither does it forbid it; 3.1.4 does not have the narrowness of scope that
you say it does.  I agree that this is poorly-worded and needs to be
clarified.

Note that the example on A.3.3. specifically shows this usage.  Granted that
there are broken examples in 822 for other reasons, but this backs up my
memory of a WG intention to allow it.

I wouldn't mind outlawing it, but with a "must parse it if you get it" for
compatibility with the past.

I also observe that 3.4.2 debunks the myth that LWSP is permitted inside
domain names, examples to the contrary notwithstanding.  Basically, there were
a lot of practices permitted by the syntax (and encouraged in 733) which
operational experience proved to be problematic.  The 733 multiple-at syntax,
for example, was banned because it crashed a certain mailer (hence the reason
why I introduced the infamous %-kludge).

> In other documents you have such things as:
>    unsubscribe_obs ::= "UNSUBSCRIBE" SPACE "MAILBOX" SPACE mailbox
> instead of:
>    unsubscribe_obs ::= "UNSUBSCRIBE MAILBOX " mailbox

In IMAP (which is where this example comes from), there is no free insertion
of whitespace, and the primary purpose for this was to prevent bugs from being
introduced in the syntax by document reformatting.