Replying to the reply.

Yes, which is why I consider the keys for the Exchange server questionable, as there is no way to disprove intrusion into those systems.

My claim surrounds gmail.com and the set of emails that passed through gmail.com. I am not aware of an intrusion into Google's systems that would have obtained highly protected keys. This also limits the number of actors who could forge the complete collection of messages obtained from a gmail.com account.

(i.e. the only thing obtained was a password, not system level access.)

If the attachments are BASE64 encoded and part of the MIME source, they should also be protected by the DKIM signature.

As far as any documents obtained from blogspot, I have no assertion to make reguarding the integrity of those message contents. The use a specific cracked version of Office may explain the document summary information not matching the proclaimed nationality of the publisher of the documents on blogspot.

I object to the (sometimes deliberate) conflating of the multiple collections and sources and the attendant implied discrediting of all be ine.

This is a forum that I hope values technical explainations and inquiry, many forums have their own version of reality.

May the truth be known, whoever is damned or praised.

If you're talking about email specifically, and if the email server has DKIM, and if the keys are secure (if the hacker can break into the server to steal emails, are you sure they didn't steal the key too?), then yeah. But many document dumps include a lot of stuff that isn't just emails, and many email document dumps probably aren't fully covered by DKIM (I say probably because I haven't checked, nor am I really in a position to do so) or the DKIM key may not necessarily be secure (if the email server itself is hacked, it may not be; if the user login to the email was hacked, presumably it will be).