Given that your emails are publicly available, what's stoping anyone from using them as a template for forgeries? I don't think there's anything in those header

Given that your emails are publicly available, what's stoping anyone from using them as a template for forgeries? I don't think there's anything in those headers that couldn't be forged (disregarding that Ceglia seems to be terrible at forging documents, of course) DKIM headers contain a cryptographic signature of the sender's email address, subject, and body, so I think that would be pretty decent proof, but unfortunately DKIM wasn't introduced until 2006.