A method of automatically processing e-mails wherein the e-mail is tagged by the sender with a unique identifier so that the e-mail can be automatically routed or filed. The unique identifier is encrypted to protect it from unauthorized tampering or decoding to avoid misidentification or fraudulent labelling...http://www.google.ca/patents/US7730139?utm_source=gb-gplus-sharePatent US7730139 - Asynchronous tamper-proof tag for routing e-mails and e-mail attachments
