Re: [dmarc-ietf] Recipient domain in aggregate reports (#23)

Matthäus Wander <mail@wander.science> Sat, 08 May 2021 12:29 UTC

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From: =?UTF-8?Q?Matth=c3=a4us_Wander?= <mail@wander.science>
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Date: Sat, 8 May 2021 14:29:11 +0200
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Subject: Re: [dmarc-ietf] Recipient domain in aggregate reports (#23)
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Laura Atkins wrote on 2021-05-08 13:59:
>> What happens to the existing "envelope_to"?
> 
> The proposal objected to was adding a new piece of information to pass
> along information that would allow reconstruction of a forwarding pathway. 
> 
>     Case 1: Identify mail flows along forwarders.

This was not meant as a proposal. It is an explanation of what is
possible with the envelope_to that exists in the spec already:
<https://tools.ietf.org/html/rfc7489#page-69>

> The current system does not allow for reconstruction of the forwarding
> pathway.

I agree in that envelope_to makes it easier for reconstruction of the
pathway, but disagree otherwise. DMARC reporting in principle allows for
reconstruction of the pathway, as noted in the privacy considerations:
<https://datatracker.ietf.org/doc/html/draft-ietf-dmarc-aggregate-reporting-02#section-6.1>
Other proposals in the current I-Ds contribute to this privacy threat
and may be worth a separate discussion:
- #57 requires reporting of selectors, which can be exploited for tracking.
- #62 makes reporting mandatory, which leaves the mail receiver with no
means to mitigate the privacy threat.

Regards,
Matt