Well it can take a while, if afte a day though it still hasn't arrived i would suspect something went wrong with it. I'm not sure if FOD can cancel email registrations if they want, just give it a little more time and try again if it doesn't work.
Just something to note, i think if you register with a new hotmail account you have made, but you register on FOD with that email BEFORE you activate your hotmail account it doesn't work, this is what happened in my brothers case anyway. Not sure about other email providers.
