@jwildeboer I got an email a few minutes ago from a reader of my mailing lists who noted that he was one of the designers of the SPF/DMARC/DKIM ecosystem, pretty much agreeing with my assertion that this isn't really as big a deal as being made out, because so much spam comes now from completely legit (but "fake") domains that pass all these checks.
@lauren Sure. I'd agree to that too. The bigger problem is that this flaw can severely damage the reputation of small(er) servers, getting them added to blacklists of the Big Mail oligopoly. That's why we mail admins of small servers are (forced to) always working hard to mitigate any possibility of that happening. But mitigations have been published by postfix, exim, sendmail. What bothers me is that this could have all been solved months ago, if done in a different way :(