Re: [dmarc-ietf] ARC vs reject

"Murray S. Kucherawy" <> Mon, 07 December 2020 05:30 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 1912D3A1011 for <>; Sun, 6 Dec 2020 21:30:43 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.097
X-Spam-Status: No, score=-2.097 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id 75v8pWY07WBD for <>; Sun, 6 Dec 2020 21:30:41 -0800 (PST)
Received: from ( [IPv6:2607:f8b0:4864:20::e2a]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id B56CB3A0CEF for <>; Sun, 6 Dec 2020 21:30:41 -0800 (PST)
Received: by with SMTP id x26so6928445vsq.1 for <>; Sun, 06 Dec 2020 21:30:41 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=K2yGdNgthQwKEDk0TPDCw9I74WzRUEX1lUch4QC1+vI=; b=s8SNQe9Da5LDUkqCmgn3ZWSEYKO1HR6a68RWi7EbP42H/UoO2gT/eiTrGYDNgVwxpP NZNzj1DELZ6xvLsg9n+zVwAPWPIhQIZ6iGGSyEW6G9BIwg0t4+MSIRLfeOGUhLIDEcra YrwsIwG2LxZk+sVG8ln3LNyJZoAq0KUAwYZzyGUYtGzZVq1fQrgeuCQFo9vo/koLmshr qemWtsntNWPENpbE6NoRST0dICpXpFpfdRK46kx9PFGVDCljrv/Tu6105UIh2N6H681x YPvaZOoMGygor5o2iMVTb8jF1rIHdDs/boy2Hb3bBo5NuSXlaUDCQMalO3tZzuIvitWY 31Kg==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=K2yGdNgthQwKEDk0TPDCw9I74WzRUEX1lUch4QC1+vI=; b=W94OQjXFg/+8Mv2zGCb2YEFzhVZAKoU00M+pCH+ii8TKdURVA89N54i6QBonMv+810 w3ZE2U1L7jZkuN636T6P0VPmR8LHlYkU1vqtWSCqS5HzVDBQk/9JyqXrRd5pAfM4iYPY pDSlrYdORtFddZd8DbCmn86oO+lh0irc0lAs6qNUymzyPAQjyODppXEXYf98MJeWaFhd Rv0b1y01beFyogdlJlu2Bxhbe5v1ViY1UhnGV57ocvLHrh/LSFFO/mRRW0kl82uqHUK3 TqWx9zQRqmUHwJyPm5J/+mqxfM20Rb7W5YgEbzyMGxjkIj0EQFpo0YvAz2Sd5HTafkJO O6sA==
X-Gm-Message-State: AOAM533NDjgK5pREjCX6/BxWCcAI7C63uZXwJjG60SejPHKUJ6W9ieH+ DGVwF9mV6qkOTXUSjTjS/47IICOM0XGTQ87JBxI=
X-Google-Smtp-Source: ABdhPJwljpwFZCH6en+6EzTqqCJ6g2PlybRb/GluK3ws3M6olODOTsnEke7EWEOKsJZ73DNuOLpxo2cENunVob5wl2Q=
X-Received: by 2002:a67:f7c8:: with SMTP id a8mr10728136vsp.54.1607319040517; Sun, 06 Dec 2020 21:30:40 -0800 (PST)
MIME-Version: 1.0
References: <20201205210351.DB78E2904420@ary.qy> <> <> <> <> <> <> <> <>
In-Reply-To: <>
From: "Murray S. Kucherawy" <>
Date: Sun, 6 Dec 2020 21:30:28 -0800
Message-ID: <>
To: Michael Thomas <>
Content-Type: multipart/alternative; boundary="000000000000736b6605b5d920ea"
Archived-At: <>
Subject: Re: [dmarc-ietf] ARC vs reject
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Domain-based Message Authentication, Reporting, and Compliance \(DMARC\)" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Mon, 07 Dec 2020 05:30:43 -0000

On Sun, Dec 6, 2020 at 9:24 PM Michael Thomas <> wrote:

> An idea that i've been rolling around in my head is that the MLM could
> give a sed-like script to rollback the changes. since they know their
> modifications, they can obviously express how to unmodify them. it may have
> less issue with the mime hackery you were thinking about.

You'd need a way to assert, and then evaluate, that something equivalent to
"s/.*/spam/g" is a transformation you're not willing to reverse and say
"yep, we're good."  I don't know how you'd go about automating that.

> But as far as your point about spam vectors it is surely just as true
> about ARC, right? at least with recovering the original text i have the
> ability to remove all of the transforms and deliver the original text.  ARC
> not so much. it's all or nothing on the trust front.
> But I really think the key thing about all of this is figuring out what
> defines success. That is the most important thing by far.
I think ARC, like PSD, is meant to run for a while and see what we've
learned from it.  Maybe it's the silver bullet, or maybe it's ineffective
complexity.  That should be part of the experiment's definition; Section 11
of the ARC RFC does try to capture all of that.