#1 - July 7, 2010, 11:31 p.m.
Do you list the e-mail address on the site anywhere? That is usually how that information is gathered, by viewing public guild pages and grabbing contact addresses for the members. If you believe a site has been compromised though, Wakatu, I'd highly recommend contacting them directly and letting them know. If there is a leak they may not be aware of it to plug it up.
You should be able to use the following link to contact them. :)
http://www.wowstead.com/contact.php