IETF Logo Mail Archive

Re: [dmarc-ietf] Nitpicky questions about DMARC record syntax

"John Levine" <johnl@taugh.com> Wed, 16 January 2019 19:18 UTC

Return-Path: <johnl@iecc.com>
X-Original-To: dmarc@ietfa.amsl.com
Delivered-To: dmarc@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 4F291130ED9 for <dmarc@ietfa.amsl.com>; Wed, 16 Jan 2019 11:18:28 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2
X-Spam-Level:
X-Spam-Status: No, score=-2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1536-bit key) header.d=iecc.com header.b=w2WX/JJE; dkim=pass (1536-bit key) header.d=taugh.com header.b=AajVMZhA
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id MIMZ6rluMxO0 for <dmarc@ietfa.amsl.com>; Wed, 16 Jan 2019 11:18:26 -0800 (PST)
Received: from gal.iecc.com (gal.iecc.com [IPv6:2001:470:1f07:1126:0:43:6f73:7461]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 62703130ED6 for <dmarc@ietf.org>; Wed, 16 Jan 2019 11:18:26 -0800 (PST)
Received: (qmail 66947 invoked from network); 16 Jan 2019 19:18:24 -0000
DKIM-Signature: v=1; a=rsa-sha256; c=simple; d=iecc.com; h=date:message-id:from:to:cc:subject:in-reply-to:mime-version:content-type:content-transfer-encoding; s=1057d.5c3f8380.k1901; bh=m7vLJrUdqYcYVJii+O5ogLyMoY/QCanOZA81lKkV+j8=; b=w2WX/JJE2ZN+4FEF6eqYPp0jOJ8reBNxddqXaFgC46nErMx1oYrb6kPNlXPdvytnGisAzho3nTHsRkRlK5k8ii92c/USfy6OKWJQ+spu6sRs1Kj+K1ZXbdmifWWvJUk2jklSpCPCfQWDOSjJ8XQSBXIp5uMQaNpJokbhNDymExDDFNiqW1ofkOwvnDHvXtwbQWRnpmk1yvLsFFKxbgg64n39LmLer0OiMIb2PjVaNqsUVgaD3RC+qiu8BH541qI6
DKIM-Signature: v=1; a=rsa-sha256; c=simple; d=taugh.com; h=date:message-id:from:to:cc:subject:in-reply-to:mime-version:content-type:content-transfer-encoding; s=1057d.5c3f8380.k1901; bh=m7vLJrUdqYcYVJii+O5ogLyMoY/QCanOZA81lKkV+j8=; b=AajVMZhAChmWe79IDsCqn9LAukTXvrw7zgDlk1Ag3prHzsXrEzXh8bYpciF2aBezPc2030+bNYkGuvVbUs5bH6/QbmGXcT90sctAxAOwS04EfDqZgf5xE6yp2fDRJ+H4eQGAGltR+bm+6nsXbwvS+wzRGuW2Jt+8M5KFp0xVzrwRdaTRkDCgPAZW8qZxvV1BbI2CFIrkI1JIGyu/ezJwRdjdGpSFayc8VAzaSu27J/2OCKjOj4BlT/NgF+GkSLAE
Received: from ary.qy ([IPv6:2001:470:1f07:1126::78:696d:6170]) by imap.iecc.com ([IPv6:2001:470:1f07:1126::78:696d:6170]) with ESMTP via TCP6; 16 Jan 2019 19:18:24 -0000
Received: by ary.qy (Postfix, from userid 501) id 0E64F200CC135A; Wed, 16 Jan 2019 14:18:23 -0500 (EST)
Date: Wed, 16 Jan 2019 14:18:23 -0500
Message-Id: <20190116191824.0E64F200CC135A@ary.qy>
From: John Levine <johnl@taugh.com>
To: dmarc@ietf.org
Cc: dcrocker@gmail.com
In-Reply-To: <7c8aa4a8-7d75-db07-7e97-82d9b0ffb29a@gmail.com>
Organization: Taughannock Networks
X-Headerized: yes
Mime-Version: 1.0
Content-type: text/plain; charset="utf-8"
Content-transfer-encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/dmarc/k6uMX2PlQiZE2tREOzFigLKim88>
Subject: Re: [dmarc-ietf] Nitpicky questions about DMARC record syntax
X-BeenThere: dmarc@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Domain-based Message Authentication, Reporting, and Compliance \(DMARC\)" <dmarc.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dmarc>, <mailto:dmarc-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/dmarc/>
List-Post: <mailto:dmarc@ietf.org>
List-Help: <mailto:dmarc-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dmarc>, <mailto:dmarc-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 16 Jan 2019 19:18:28 -0000

In article <7c8aa4a8-7d75-db07-7e97-82d9b0ffb29a@gmail.com> you write:
>If more flexibility is viewed by the community as desirable, then the 
>community should enhance the specification to allow it.  This improves 
>robustness while retaining a firm, clear and precise standard.

Do keep in mind that most of the DMARC records I've looked at follow
the spec.  They may not have the expected policy, but the syntax is
fine.  If a small minority get it wrong, I think it's better to
educate and fix them than to try to guess when someone misreads the
spec in a way that leads them to screw up the syntax of the record,
but not to screw up anything else.

Remember, that if your software rewrites an invalid record into a
correct one, you are trying to read the mind of the person who wrote
the misformed record.  I can guess what v=dmarc1 was supposed to say
but I have no clue what pct:1 is supposed to mean.  Let's not start.

R's,
John

v2.23.0 | Report a Bug | By Email