hasStartedUp = false;
  public synchronized void shutdown ()  {    //  Kill all the inboxes    if (inboxes != null)    {      for (int i=0; i<inboxes.length; i++)      {        // unregisterMailData ();        inboxes[i] = null;      }      unregisterMailData ();      inboxes = null;    }    //  Halt and get rid of all the inbox threads    stopMailReadingThreads();hasStartedUp = false;  }