I like the idea of non-repudiation, let the chips fall where they may when such authentic email is maliciously dumped. Perhaps a simple timestamped based appen

I like the idea of non-repudiation, let the chips fall where they may when such authentic email is maliciously dumped. Perhaps a simple timestamped based appendage can be added for the sake of email client authentication. In other words reject the email if the signature is older than a few hours/minutes.