Here it is...
http://www.flyertalk.com/forum/Forum5/HTML/006176.html
The email confirmation is only recognized for domestic travels. You'll need a fax or hard copy for transborder/international flights.
They should either send you a fax or snail mail. Most of the time, I get both. The worse part is the hard copy usually don't arrive in the mail until my travel is completed so I don't even bother opening it sometimes.