Abstract: A Reachback email system includes methods and software products for intercepting a sent email message from an email client, algorithmically determining a first Reachback URL from an email address of the email client, adding the first Reachback URL to the sent email message to form a sent Reachback email message, digitally signing the sent Reachback email message, sending the sent Reachback email message to at least one recipient, publishing Reachback validation information (RVI) accessible by the at least one recipient using the first Reachback URL, intercepting a received Reachback email message before delivery to the email client, retrieving RVI for the received Reachback email message using a Reachback URL, validating the RVI, the Reachback URL and the Reachback email message contents, providing an indication of the Reachback email message validation, and delivering the received Reachback email message to the email client.