function AddMSMailHeaders() {
      $MSHeader = "";
      if($this->Priority == 1)
         $MSPriority = "High";
      elseif($this->Priority == 5)
         $MSPriority = "Low";
      else
         $MSPriority = "Medium";

      $MSHeader .= sprintf("X-MSMail-Priority: %s\r\n", $MSPriority);
      $MSHeader .= sprintf("Importance: %s\r\n", $MSPriority);

      return($MSHeader);
   }