[Mailman-Developers] dkim-signature headers

[Michael Thomas]

Bob Puff wrote:
> I confess not having read up on Domain Keys.. I did get into SPF a little, but
> understand its flaws as well.
>
> If a bad DK isn't bad, then how is this supposed to help spam?  I mean, if the
> mere presence of some signature in the headers will increase the likelihood of
> an email being delivered (or at least help it NOT be tagged as spam), surely
> the spammers will pick up on this, and the whole benefit lost.
>   
DKIM isn't about "solving" spam per se. It's about accountability. If
you know about a source, you can treat it differently. DKIM allows you
to know the source. That goes for both good and bad sources of mail.

> Example:
>
> Spammer takes a legit message from a DK sender, replaces it with his spam, and
> blasts it out with the original DK headers.  The message has obviously been
> altered, and contains spam.  Would it not be right to reject this message,
> since it fails the DK check?
>   
It's no more right to reject based on a signature failure than any other
single test; how strong a weighting you give a signature failures depends
on a myriad of things -- if you want to prevent false positives. In fact,
I'd say that one of the DKIM provides is a better way to prevent false
positives rather than detecting spam per se. If you know and trust
a source, mail talking about v**gr* is more likely to be legit. Mail without
signatures or with broken signatures is just put through the normal unknown
source spam filter, so it's just neutral rather than spammy.

       Mike