get https://sandbox.dmhisp.com/SecureMessagingApi/Message//Mime
This method is used to retrieve a DataMotion message in standard MIME format. Senders and recipients are the only users that have access to the message and will be permitted to retrieve this basic DataMotion header information and the Security Envelope. The message sender is the only user that will be permitted to retrieve detailed tracking information. When a message is retrieved using this function, tracking information will automatically be written indicating the message was read by the recipient.