Re: empty quoted strings and other oddities

Russ Allbery <rra@stanford.edu> Tue, 01 October 2002 04:27 UTC

Received: (from majordomo@localhost) by above.proper.com (8.11.6/8.11.3) id g914Ruv06038 for ietf-822-bks; Mon, 30 Sep 2002 21:27:56 -0700 (PDT)
Received: from windlord.stanford.edu (windlord.Stanford.EDU [171.64.13.23]) by above.proper.com (8.11.6/8.11.3) with SMTP id g914Rtv06034 for <ietf-822@imc.org>; Mon, 30 Sep 2002 21:27:55 -0700 (PDT)
Received: (qmail 15202 invoked by uid 50); 1 Oct 2002 04:27:51 -0000
To: ietf-822@imc.org
Subject: Re: empty quoted strings and other oddities
References: <3D991B36.1070700@alex.blilly.com>
In-Reply-To: <3D991B36.1070700@alex.blilly.com> (Bruce Lilly's message of "Mon, 30 Sep 2002 23:49:10 -0400")
From: Russ Allbery <rra@stanford.edu>
Organization: The Eyrie
Date: Mon, 30 Sep 2002 21:27:51 -0700
Message-ID: <ylit0msrzs.fsf@windlord.stanford.edu>
Lines: 24
User-Agent: Gnus/5.090008 (Oort Gnus v0.08) XEmacs/21.4 (Honest Recruiter, sparc-sun-solaris2.6)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Sender: owner-ietf-822@mail.imc.org
Precedence: bulk
List-Archive: <http://www.imc.org/ietf-822/mail-archive/>
List-ID: <ietf-822.imc.org>
List-Unsubscribe: <mailto:ietf-822-request@imc.org?body=unsubscribe>

Bruce Lilly <blilly@erols.com> writes:

> RFC 2822 permits (as did 822) a quoted string which
> consists solely of a pair of DQUOTE characters.  It's
> not clear what the semantics of that are or ought to be.

> Likewise, a domain literal can consist solely of the
> square brackets.

> The combination of the two means that the following is
> syntactically valid as an angle-addr or msg-id:

> <""@[]>

> Perhaps these empty contructs could be relegated to obs-
>   status in the next revision, with the generate syntax
> changed to use 1* instead of * for the content within a
> quoted-string and domain-literal.

qmail makes use of this to prevent internal double-bounces from bouncing
again.  Whether that use is worthwhile or not is possible debatable.

-- 
Russ Allbery (rra@stanford.edu)             <http://www.eyrie.org/~eagle/>