In the email provide them a code, since on the WoW page they ask for a beta code.
Watch this site: WoW -> Beta Sign Up -> Form
So add a box for the made up beta code.
Also if you want, you could make a new trustworthy phishing site..
Copy that world of warcraft page with like Flashgot or any other site copier, and use that instead of the WotLKdesign since its so well known by now..
If you can buy a domain that looks like the World of warcraft domain
example: worldoffwarcraft, World0fWarcraft, wow-evrope and so on..
Get a host with a ftp, upload all the needed files you copied from the WoW site, make a map called misc, inside that map rename the index.html file to beta-signup.html.. now enter http://www.DOMAIN(dot)com/misc/beta-signup.html and it will look safe for the ones to be scammed..
If you dont want to spend money on the domain try with fbox.us, im still waiting for my domain there, might take a long time to receive the domain aswell..