Comment 5 for bug 386667

We could and probably should warn when an email address associated with multiple teams is invalidated, but I agree that it's probably not enough of a reason to prevent multiple teams from having the same contact address. Robert's original use case is a valid one if we're serious about distinguishing teams for communication and teams for permission. OTOH, if promoting mailing lists to first class objects obviates the need for the former, then maybe we're back to the status quo.