Re: Last Call: <draft-levine-herkula-oneclick-04.txt> (Signalling one-click functionality for list email headers) to Proposed Standard

"John Levine" <> Mon, 19 September 2016 22:37 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 4D97F12B579 for <>; Mon, 19 Sep 2016 15:37:49 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.901
X-Spam-Status: No, score=-1.901 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id hDQt51UVc7Gi for <>; Mon, 19 Sep 2016 15:37:44 -0700 (PDT)
Received: from ( [IPv6:2001:470:1f06:1126::2]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 0AB1B12B56E for <>; Mon, 19 Sep 2016 15:37:40 -0700 (PDT)
Received: (qmail 8652 invoked from network); 19 Sep 2016 22:37:37 -0000
Received: from unknown ( by with QMQP; 19 Sep 2016 22:37:37 -0000
Date: 19 Sep 2016 22:37:17 -0000
Message-ID: <20160919223717.82743.qmail@ary.lan>
From: "John Levine" <>
Subject: Re: Last Call: <draft-levine-herkula-oneclick-04.txt> (Signalling one-click functionality for list email headers) to Proposed Standard
In-Reply-To: <>
X-Headerized: yes
Mime-Version: 1.0
Content-type: text/plain; charset=utf-8
Content-transfer-encoding: 8bit
Archived-At: <>
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: IETF-Discussion <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Mon, 19 Sep 2016 22:37:50 -0000

In article <> you write:
>It seems to me that catering to senders whose unsubscribe volume is so
>high as to overwhelm their email systems should not be a priority.

People at large mail systems tell me it's a fact of life.  Long before
this particular hack ever came up, they already had problems of
accidentally DoS'ing other mail systems by mistake when something
provoked a lot of responses.  In any event, our goal here is to help
make mail less lousy, not to make a statement about how we think
people should design their systems.

>Can you explain the DKIM requirement in more detail?  Is the MUA required
>to verify the DKIM signature?  Or is it expected to alternatively trust
>any Authentication-Results header?

That's an implementation detail.  In the most likely implementations,
it's web mail so the MDA and MUA are all the same system.

> What purpose does the DKIM signature
>serve, if there is no required correlation between the authenticated "d="
>value and the authority of HTTPS unsubscribe URI?

It gives the recipient system a handle to use to decide whether they
trust the message enough to use the list-unsubscribe and
list-unsubscribe-post.  The postmaster at the world's largest mail
system has told me that this is useful to them.

>What are the cross-origin risks in allowing the incoming mail to trigger
>a POST to a URI of the sender's choice with sender selected parameters?

I would think that it's about the same as the GET that
List-Unsubscribe already can trigger.  We've lived with that for nearly
two decades.

>The Examples in Section 7 don't have anything resembling HMAC signatures
>over the recipient + list data, or opaque nonces that identify both.

The examples in the upcoming -06 are slightly opacified.