Authenticating Email Using DKIM and ARC, or How We Analyzed the Kasowitz Emails

Suppose a source forwards you an email sent by a public figure. How do you make sure it isn’t fake?

A source forwarded to my colleague a vulgar, threatening email from Marc Kasowitz, at the time the President’s personal lawyer. I verified the email hadn’t been tampered with by the source – so we could publish the story.

Then, I wrote a technical how-to to hopefully help other journalists to authenticate emails using the same tools I did: pair of arcane pieces of the email system called DKIM and ARC.