[XorNot]

They've validated 1. of the emails, not "some": https://github.com/robertdavidgraham/hunter-dkim

And frankly, possession of a single legitimate email's source text, for an intermediate-profile individual from a corporate account, doesn't somehow prove anything else (which again: is zilch - nothing else about this story is verifiable - it reeks of an intelligence op, especially since Rudy Giuliani is known by the FBI to be routinely in contact with known Russian intelligence operatives).