Description

   The first time the MAIL$MESSAGE_GET routine is called, the
   message information is returned for the first requested message,
   and the status returned is MAIL$_MSGINFO. Subsequent calls to
   MAIL$MESSAGE_GET with the MAIL$_MESSAGE_CONTINUE item code return
   the message text records with the status MAIL$_MSGTEXT, until no
   more records are left, when MAIL$_NOMOREREC is returned.