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Re: [dmarc-ietf] WGLC ARC-16 concern on Section 5.1.2 - cv=fail should sign greedily

Dave Crocker <dcrocker@gmail.com> Wed, 15 August 2018 18:48 UTC

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To: John Levine <johnl@taugh.com>, dmarc@ietf.org
References: <20180815183022.09ED420038205D@ary.qy>
From: Dave Crocker <dcrocker@gmail.com>
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Date: Wed, 15 Aug 2018 11:48:39 -0700
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Subject: Re: [dmarc-ietf] WGLC ARC-16 concern on Section 5.1.2 - cv=fail should sign greedily
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On 8/15/2018 11:30 AM, John Levine wrote:
> In article <799c2b18-97fe-6e22-f2cf-49245ae9c65e@gmail.com> you write:
>> So the extra mechanism is intended an efficiency hack.
> 
> No, it also documents the fact that the chain was broken when it
> arrived at the cv=fail signer.  Without it, a subsequent hop can't
> tell.  It probably won't make much difference to spam filters, but
> it could be useful if you're trying to find and fix forwarders
> that make gratuitous changes.
> 
> I think there's a modest benefit to signing with cv=fail, and since
> you can't count on having a chain (even an invalid one) signing as
> if it were cv=none seems reasonable.


Modest, indeed.  Also unknown.

This is building in a permanent behavior, for a use that is, at best, 
vague conjecture.

d/


-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net

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