On Thu, 27 Jul 2006 16:15:03 -0700 Jim Fenton <fenton(_at_)cisco(_dot_)com>
wrote:
Scott Kitterman wrote:
On Thursday 27 July 2006 18:31, Jon Callas wrote:
If I use isp.example.com and they sign messages with my name and a
key (theirs
or mine, doesn't matter) and they also sign messages actually sent
by joe
spammer (another one of their customers) with my name and a key
(again,
theirs or mine), then it sucks to be me. That's the problem.
No, it doesn't suck to be you. The first letter of DKIM stands for
"Domain." It sucks to be example.com.
To clarify, by me, I meant my domain. The problem is that in this type
of
scenario, there is no way to externally distinguish between mail
actually
sent by the vanity domain owner and mail sent by another customer of
isp.example.com
I guess this means that isp.example.com is not worthy of your delegation
of signing authority to them, and you should shop elsewhere (find a more
reliable ISP, or sign your own messages). I think the ISPs will get it
right fairly quickly if they lose business as a result of not
authenticating mail submission properly (or otherwise fixing whatever
mechanism allowed Joe Spammer's message through).
Yes. What I want as a small domain owner is the ability to publish a
policy record that say that for mail sent (for some definition of sent that
we will probably have to argue about later) from my domain, the domain(s)
authorized to sign are ...
If/when I switch providers I can change the list. This is the simplest
approach I can think of to put small domain owners on the same footing as
domains running dedicates MTAs. I think from the perspective of the domain
owner it is easier than managing public keys in DNS.
For many small domains, signing themselves will be completely out of reach
due to cost and lack of expertise.
Scott K
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