> Yeah the man-off-the-street expects that if you have an email in your inbox it's proof positive that it was received like that. They don't know that you can upload counterfeit emails using imap or anything like that. Introducing non-repudiation would violate everyone's expectations and create a total mess.

If the "man-off-the-street" expects email to have non-repudiation property, then how exactly would "introducing non-repudiation" violate their expectations?