The email address to which the Message Disposition
Notification (also called 'Return Receipt') sent when the
email sent from this device is read by the receiver. The
format of this object is an e-mail address which conforms
to RFC822 and RFC1123 'addr-spec' syntax.
Some examples are
raj@helpme.com,
bob@service.com,
mtom@abc.caview.ca.us.
A set operation on this object with a invalid format will
result in an error.