Re: [ietf-dkim] list vs contributor signatures, was Wrong Discussion

On 04/30/2010 07:38 AM, McDowell, Brett wrote:
> On Apr 30, 2010, at 10:23 AM, Michael Thomas wrote:
>
> > On 04/30/2010 07:05 AM, McDowell, Brett wrote:
> > > In that scenario, if the MLM re-signing solution has been deployed by Y, 
> > > and DKIM+ADSP has been deployed by X&   Z, and Z has chosen to take action 
> > > on X's ADSP policies... the only thing Z is trusting Y to do is validate 
> > > incoming DKIM signatures, re-sign the messages with its own DKIM signature, 
> > > and pass it along with the A-R results that convey what was done.  Z is not 
> > > trusting everything and anything that might ever come through Y.
> > >
> > > I think that's a reasonable level of trust to expect mailbox providers to 
> > > have in mail lists who assert that they do this.  Rogue mail lists will 
> > > stop being trusted but only after they have "lost" the trust that was 
> > > granted to them via their standards-based assertion (we would probably need 
> > > to spec out how a MLM advertises that they indeed conduct flows in this 
> > > manner) that they perform these functions on incoming mail.
> > >
> > > Again, I'm not saying this is the best or most elegant way of handling the 
> > > problem of properly authenticated mail not being able to traverse mail 
> > > lists, but it seems worthy of further discussion as an option.
> > Yeahbut... there are zillions of mailing lists out there. How do you know 
> > the good ones
> > from the bad ones? Keep in mind, of course, that bad guys can resign too, 
> > and they can
> > easily make themselves look like a mailing list if that's something that 
> > gives them
> > advantage.
> Indeed.  But mailbox providers all have their own secret sauce for figuring 
> out reputation of senders that I believe they could apply to this new flavor 
> of sender -- meaning MLM's who adopt the MLM-DKIM spec we seem to be debating 
> the virtues of developing -- without too much overhead.
>
> > If the solution is some sort of (third party) reputation/whitelist, then 
> > there's really
> > not much for us to do, right?
> I think we still need this spec I'm starting to refer to as MLM-DKIM to 
> specify both the proper way of conducting this re-signing&  reporting 
> practice and how the MLM advertises that they follow it.
>
> > Even with your discardable adsp setting, it becomes a
> > matter of the order of checks at the receiver's gate (eg, whitelist first, 
> > then adsp...)
> But since mailbox providers already manage reputation at scale, how much of a 
> burden is adding this bit to the mix?  Remember this only affects mailbox 
> providers who have decided to do DKIM blocking based on ADSP discardable 
> policies (for some, if not all senders).
Let's put aside whether there's something new here for the moment (i've not had 
my
coffee yet...). By all rights, we should not be having this conversation right 
now
at all because you have set adsp discardable. So even if we adopted some 
bcp-like
advise for mlm and receivers, it would be years if not forever before we could 
have
a reliable conversation on this and other lists again. Maybe at paypal that's an
acceptable tradeoff (?), but at my previous employer, all standards work, for 
one,
would cease and there would be lots of engineers with pitchforks and torches.

So what I'm getting at here is that I'm having a hard time understanding how the
bootstrap doesn't fail for most sending/receiving entities. As I'm sure you 
know,
false positives drive mail admins to complete distraction... which is the 
situation
it looks to me that you're willing setting up.

That said, you (paypal) are far braver than I am, but if you can make this to 
work
somehow as a large enterprise that would be a pretty amazing accomplishment.

Mike
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