Abstract: A Postal Authority regulated e-Mail messaging application is provided over a public network to a plurality of mailers and addressees using authenticated transaction records. The application transmits at least one e-Mail message through at least one e-Mail account configured for a specific class of service. The application creates transaction records relevant to the specific class of service based upon details of completed transactions. Electronic postmarks are obtained to authenticate transaction records. Authenticated transaction records are sent to the mailer. A unique identifier of an electronic postmark is embedded in the e-Mail message. The e-Mail message incorporating the unique identifier is sent to at least one addressee. Authenticated e-Mail messages and transaction records are created and protected from undetectable modification.