A former business partner is claiming that he sent our firm an email message over a year ago. While we most likely received email messages from him on that date, we never received the information he claims was in the original email. He has forwarded the email message to us. However, we understand that it is fairly easy to modify a forwarded message. If we had access to his laptop and email, is there a way to authenticate the email message in his sent box? How easy is it to modify the body of an email message in the sent box?