There are lots of rumours on messageboards about various e-mail addresses for the stars of the Harry Potter film.
However, you should beware of hoaxes, because it is very unlikely that the real thing would be spread around.
If you think you are chatting to Rupert or Daniel - you might well be chatting to a fake. So please be careful.
There is no official way of getting hold of the actors' e-mail addresses.
But the good news is that many of the cast members have their own official websites. But again, please make sure you are on their official site.