Experience with DKIM signatures and DCC

> I wouldn't do anything with DKIM failure at this point, since there are way 
> too many reasons that legit mail could arrive with a valid signature.

Ahem, with an INvalid signature.

>
> Whitelisting DKIM sigs from people you know and white and blacklisting of IPs 
> with particularly good and bad histories should work well.
>
> R's,
> John
>