«These things indicate that accounts should have transitory, one-to-many relationships to email addresses, rather than email addresses serving as a key.» The o

«These things indicate that accounts should have transitory, one-to-many relationships to email addresses, rather than email addresses serving as a key.» The only requirement for the email to be a key to the account is the association of one email to one person. A person can have more than one email, at different times or at the same time. The only thing that can't happen is one email mapping to two individuals. Full circle: the majority of emails do map to one individual and the cases where they do not map, are not enough to preclude the use of emails as keys. Perhaps the confusion occurs because you think I'm defending email as a primary key for the account. I'm not. It's one key, not the primary key.