A dead e-mail identification locator discovers dead e-mail addresses without forwarding messages to valid recipients. Existing headers in the mail protocol are extended to include a test header. A mail server that supports the protocol extension of the present invention may send a reply if the address...http://www.google.com.au/patents/US6959324?utm_source=gb-gplus-sharePatent US6959324 - Method and apparatus for adding data attributes to e-mail messages to enhance the analysis of delivery failures
