i think it is legal. i have sent a lot of fanmail to home adresses who can be found on for example whitepages.
Usually i use the address once or twice. Maybe it would be Stalking if you sent thousands of fanmail there.

Hi, I've seen some people on here that say that they contact a celebrity by sending the fan mail to their home address. Is it legal to do that? Wouldn't it look as if you're stalking the celebrity since you know their actual home address?

Thanks in advance,
Leon