Re: [apps-discuss] Comments on Malformed Message BCP draft

Tony Finch <dot@dotat.at> Mon, 18 April 2011 12:20 UTC

Return-Path: <fanf2@hermes.cam.ac.uk>
X-Original-To: apps-discuss@ietfc.amsl.com
Delivered-To: apps-discuss@ietfc.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfc.amsl.com (Postfix) with ESMTP id 2578CE07BC for <apps-discuss@ietfc.amsl.com>; Mon, 18 Apr 2011 05:20:02 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.895
X-Spam-Level:
X-Spam-Status: No, score=-4.895 tagged_above=-999 required=5 tests=[AWL=1.704, BAYES_00=-2.599, RCVD_IN_DNSWL_MED=-4]
Received: from mail.ietf.org ([208.66.40.236]) by localhost (ietfc.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id wl59D9mDKqHD for <apps-discuss@ietfc.amsl.com>; Mon, 18 Apr 2011 05:19:58 -0700 (PDT)
Received: from ppsw-51.csi.cam.ac.uk (ppsw-51.csi.cam.ac.uk [131.111.8.151]) by ietfc.amsl.com (Postfix) with ESMTP id C6340E06ED for <apps-discuss@ietf.org>; Mon, 18 Apr 2011 05:19:57 -0700 (PDT)
X-Cam-AntiVirus: no malware found
X-Cam-SpamDetails: not scanned
X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/
Received: from hermes-2.csi.cam.ac.uk ([131.111.8.54]:52457) by ppsw-51.csi.cam.ac.uk (smtp.hermes.cam.ac.uk [131.111.8.158]:25) with esmtpa (EXTERNAL:fanf2) id 1QBnQj-0001RT-Xr (Exim 4.72) (return-path <fanf2@hermes.cam.ac.uk>); Mon, 18 Apr 2011 13:19:49 +0100
Received: from fanf2 (helo=localhost) by hermes-2.csi.cam.ac.uk (hermes.cam.ac.uk) with local-esmtp id 1QBnQj-0007L0-FX (Exim 4.67) (return-path <fanf2@hermes.cam.ac.uk>); Mon, 18 Apr 2011 13:19:49 +0100
Date: Mon, 18 Apr 2011 13:19:49 +0100
From: Tony Finch <dot@dotat.at>
X-X-Sender: fanf2@hermes-2.csi.cam.ac.uk
To: "Murray S. Kucherawy" <msk@cloudmark.com>
In-Reply-To: <F5833273385BB34F99288B3648C4F06F1343319E5F@EXCH-C2.corp.cloudmark.com>
Message-ID: <alpine.LSU.2.00.1104181313310.19348@hermes-2.csi.cam.ac.uk>
References: <F5833273385BB34F99288B3648C4F06F1343319E22@EXCH-C2.corp.cloudmark.com> <CEDB17EC-80CE-49B5-91C1-FBCB0449BBA5@network-heretics.com> <4DA8542F.9040003@tana.it> <F5833273385BB34F99288B3648C4F06F1343319E51@EXCH-C2.corp.cloudmark.com> <4DA876B6.9050700@dcrocker.net> <3111.1302886470.781218@puncture> <4DA878B4.9060007@dcrocker.net> <B5B267BE-98C6-40F3-9D37-0CE95AE5F1D4@network-heretics.com> <F5833273385BB34F99288B3648C4F06F1343319E5F@EXCH-C2.corp.cloudmark.com>
User-Agent: Alpine 2.00 (LSU 1167 2008-08-23)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: Tony Finch <fanf2@hermes.cam.ac.uk>
Cc: ietf-822 <ietf-822@imc.org>, Keith Moore <moore@network-heretics.com>, General discussion of application-layer protocols <apps-discuss@ietf.org>, "dcrocker@bbiw.net" <dcrocker@bbiw.net>
Subject: Re: [apps-discuss] Comments on Malformed Message BCP draft
X-BeenThere: apps-discuss@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: General discussion of application-layer protocols <apps-discuss.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/apps-discuss>, <mailto:apps-discuss-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/apps-discuss>
List-Post: <mailto:apps-discuss@ietf.org>
List-Help: <mailto:apps-discuss-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/apps-discuss>, <mailto:apps-discuss-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 18 Apr 2011 12:20:02 -0000

Murray S. Kucherawy <msk@cloudmark.com> wrote:
>
> I don't think this work is targeted at intermediaries.  In fact, I'd be
> completely fine with expressly saying it's meant to address processing
> at ingress MTAs only.

If you are going to make that kind of restriction, it should happen at
submission servers only.

There is a history of MX servers making "helpful" fix-ups to messgaes
(e.g. inserting missing message-id or from headers) before handing them
over to anti-spam software, which can make spam/legit checks invalid in
both the positive and negative senses. So I think MXs should be as
transparent as possible so that downstream security software is less
likely to have interop problems. Intermediate relays should also be as
transparent as possible.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
Rockall, Malin, Hebrides: South 5 to 7, occasionally gale 8 at first in
Rockall and Malin, veering west or northwest 4 or 5, then backing southwest 5
or 6 later. Rough or very rough. Occasional rain. Moderate or good,
occasionally poor.