Most BB have ring tones and vibrate options. Are you saying that if you get a single email, you want it to ring until to throw it out the window?
Now that I would never want, I put mine to sleep at 11pm and it doesn't wake up until 7am weekdays and 9am weekends. But, I understand for the world of on-call people or emergency response it would be a must. Sure might get expensive if you kept throwing it out the window though