i belive how it worked for the US one is that they have different waves.
a select # will be picked at the start, and then later on when they add in more people. this is for various reasons from my viewpoint, bliz may say something else.
1) server stress: if you have a server and youve got a couple thousand people's info to keep track off and the server cant handle it, you will have a lot of pissed off people. by letting people come in a few at a time, you can keep an eye on the stress and see what its limit is.
2) in each 'push' new content is added: sometimes for lower levels, sometimes for higher. if lower level content is added in, the newer people added in for the push are now able to test it.
3) lastly: when the game goes live, its going to follow the same kind of style. game comes out, a bunch of people join, a couple (insert time frame here, days weeks months) later another 'wave' comes in. this is used for not only econonmy use, making sure lower level items are still in demand from people who are on thier first char, not seventh, but again for server stress and other various reasons...
and to answer your real questions about the emails.... im not sure, check out www.worldofwarcraft.com to find out.
Ksetrat - Warlock 70
Xantcha - Warlock 60