I will agree that 24 hours did not seem long, but surely an email would hit everyone whether they had worked on the live event or not. I suppose a lot depends on the definition of the achievement. That being said the verification code could equally have been obtained by people who came along after the event had ended. Maybe we need a coded email address we have to message during the early stages of the mission or something? I think this may be a tough one to iron out for the devs.