warren, are you any good at electrics ???
i'd be wire'ing my letterbox up to the mains!
do it off a plug, keep the voltage low cos you dont want to kill him, just turn his dick black

you will need something to power in the circuit (bulb) and also wire up a cctv camera and show us the vid
Also, make sure you can remove the circuit quickly with crocodile clips or something like that incase plod arrives, cos its quite illigal.
and if any plod are reading this thread, this is only a joke, not to be taken litterally!