@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 :(
@lauren And (at least according to some early checks) this flaw isn't limited to DMARC spoofing. It could potentially be used for phishing and other abusive attacks too. This is why sendmail, exim and postfix (and more, I guess) have decided to treat this with high priority.