-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org [mailto:ietf-dkim-
bounces(_at_)mipassoc(_dot_)org] On Behalf Of John R. Levine
Sent: Friday, April 23, 2010 9:39 AM
To: Ian Eiloart
Cc: ietf-dkim(_at_)mipassoc(_dot_)org
Subject: Re: [ietf-dkim] Why mailing lists should strip DKIM
signatures
I sign all my outgoing mail, and I have a feedback loop set up with
Yahoo, which being very modern and advanced keys on signatures, not
IP
addresses. A few days ago I sent some messages to one of the
Freebsd
mailing lists. Today some Yahoo user who subscribes to that list
hit
the spam button. Freebsd's list software (Mailman, I think)
doesn't
sign, and doesn't strip any headers. So what happened? Yahoo saw
my
signature and sent the reports to me, which was of course useless
since I don't run the list.
Would this still be an issue if the lists were signing the outbound
mail?
You'd hope that Yahoo would then send the feedback reports to the
list
owner.
Probably not. It depends if the list owner has an FBL of their own,
which
small senders generally don't.
If that's the case, then the preferred behaviour must be to sign the
message,
DKIM header included.
The list should certainly sign, but the old signature has to go, since
the
reputation of a list's mail belongs to the list, not the contributors.
R's,
John
John raises an interesting question. It has been asserted that signing
for a message is making an assertion of responsibility for it.
In the example John provides, the DKIM signature survived intact (or did
Yahoo send the report through the FBL based on a broken signature?).
If John is making some assertion of responsibility for his message by
signing, what is the limit of his responsibility as the message flows
through the ecosystem? Where is the RFC that says his signature should
be stripped? If the list stripped his signature and someone modified
what he wrote is this a failure of DKIM or is it something else? What
are we collectively (and individually) trying to achieve if we are
signing the body and not just the headers?
When the person hit the "this is SPAM" button were they referring to
John's message or were they referring to mail from the list? How do we
know?
If there were more than one valid signature on the message where would
Yahoo send the report? Where should Yahoo send the report? What if none
of the signatures are "first party"? It has been asserted multiple times
that multiple signatures are possible and perhaps even desirable.
Just a few thoughts and questions on a Friday morning.
Mike
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