The 'domain' for Apple email addy's is either "mac.com" or "me.com". The former is the old version. Anyone joining after 200x has the new domain name, but if you were already a member, you kept the old one. New aliases get the "me" domain. But unless you close and reopen a membership, I've never heard of them changing the domain part.
Of course, even if you could have got the whole addy, I don't think it would have helped access his personal data at Apple...
White Pages pretty much has everyone with a phone listed...and with a lot of other info you may not know about...