They probably have but I guess it takes some time for all of them to get delivered. I guess that they first put the status update in each applicant's application webpage and then they sent the massive email, in that order.
Since there are lots of emails to be sent (if the data of 2010 is correct then more than 500 applicants each year) they use email software that sends an specified amount of emails per hour so the server doesn't go down, or perhaps they have policies on sending massive email at nights... (these is what they do at my office based in a developing country ).
Dunno, just guessing here...
I am happy but I won't stop the anxiety completely until I get that email!