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Re: [dmarc-ietf] Reversing modifications from mailing lists

John R Levine <johnl@taugh.com> Tue, 30 November 2021 17:30 UTC

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Date: Tue, 30 Nov 2021 12:30:39 -0500
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From: John R Levine <johnl@taugh.com>
To: Wei Chuang <weihaw@google.com>, Alessandro Vesely <vesely@tana.it>
Cc: dmarc@ietf.org
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Subject: Re: [dmarc-ietf] Reversing modifications from mailing lists
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On Tue, 30 Nov 2021, Wei Chuang wrote:
> What about adding a footer to some html mime part is poorly handled when
> using "l="?  Multipart bodies could be handled by other techniques.

See section 8.2 in the DKIM spec which says if you use l= you need to be 
careful with your MIME boundaries so naughty people can't add another part 
that overlays the real message.

I have seen lists that edit the footer into the HTML of the body, I think 
at Yahoo groups.  Don't see how you're going to describe that in a 
reversible way.

Regards,
John Levine, johnl@taugh.com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly

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