PHPMailer::getLastMessageID PHP Method

    public function getLastMessageID()
    {
        return $this->lastMessageID;
    }

 /**
  * Test setting and retrieving message ID.
  */
 public function testMessageID()
 {
     $this->Mail->Body = 'Test message ID.';
     $id = md5(12345);
     $this->Mail->MessageID = $id;
     $this->buildBody();
     $this->Mail->preSend();
     $lastid = $this->Mail->getLastMessageID();
     $this->assertEquals($lastid, $id, 'Custom Message ID mismatch');
 }