> -----Original Message-----
> From: Jeff Macdonald [mailto:[email protected]]
> Sent: Tuesday, April 27, 2010 10:05 AM
> To: McDowell, Brett
> Cc: Murray S. Kucherawy; [email protected]
> Subject: Re: [ietf-dkim] Wrong Discussion - was Why mailing lists
> should strip DKIM signatures
> 
> > That's interesting.  Let's make this concrete... I'll use myself as
> an example.
> >
> > X = me/PayPal.com
> > Y = this list/[email protected]
> > Z = Google's Gmail service [1]
> >
> > It is my assumption that someone subscribed to this list has a
> gmail.com account (or a Yahoo.com account [2]).  Therefore, my use case
> is simple.  I would hope that those of you reading this from your Gmail
> or Yahoo! accounts actually receive this message.  If Z breaks the
> signature, you won't see this.
> 
> how about Y breaking the signature? I see your message only because I
> told gmail's filtering system to not put messages into the spam folder
> for this list. Otherwise it would of gone into the spam folder.
> Looking at the source of the message, I only see the list's DKIM
> signature.

Y breaking the signature isn't relevant (in this hypothesis).  Y also says when 
it got the message from X, X's signature was intact.  That Y messed up the 
signature, making Z unable to verify it directly, is not important; Z trusts Y, 
so Z trusts Y's Authentication-Results: that says X's signature was fine when 
it got to Y.

> Should the policy statements be ignored at that point?

In this hypothesis, they could be.  Or, they could be applied.  If X's ADSP 
says "all" or "discardable", and Z trusts Y, and Y claims X's message had a 
valid signature, ADSP is satisfied.


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