She doesn't have one.
This explains everything:
link
The link is from Stephenie's official website and says (and I quote)
"For those of you hoping to find an email address or a way to contact Stephenie — I apologize. There is currently no way for fans to get in contact with her. Stephenie is still much too busy to re-open her fan email or snail mail addresses. Also, I cannot forward emails. She is in the process of writing/editing multiple books, and I think we can all agree that we would rather that she spends her time writing instead of reading thousands of emails every day."
