At 10:43 04-10-2007, Fred Baker wrote:
yes. For example, every email from @cisco.com is dkim-signed. The
IETF can automagically dump any such email that is not signed, or for
which the signature doesn't check out. I know that fred(_at_)cisco(_dot_)com is
one of many commonly-spoofed email addresses - I can tell that from
the backscatter I find in my junk box.
Cisco.com would have to publish a SSP (draft-ietf-dkim-ssp)
indicating that it signs all mail. Alternatively, one might apply
heuristics to increase the spam probability if an email from
@cisco.com is not dkim-signed.
Spam can pass SPF, Sender-ID and are even DK and DKIM signed
nowadays. One can't blame spammers for not being early adopters. :-)
TMDA may cause backscatter. That could be avoided by rejecting email
which is most likely spam at the MTA level and have the rest held for
manual review. That should decrease the amount (98%) of mail
requiring manual review. With such a system, you still need an
alternate contact channel which the sender can use to get his/her
message though if the it is rejected.
Sometimes it's easier to alleviate the problem instead of solving
it. draft-ietf-sipping-spam-05 (
http://www.ietf.org/internet-drafts/draft-ietf-sipping-spam-05.txt )
provides an interesting insight.
Regards,
-sm
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