I find it frustrating, as do my subscribers, that they can't change their own email address and keep the historical data and not get the welcome series all over again. My subscribers are not subscribed as wordpress user and thus "Manage Your Subscription" page only gives them an option to unsubscribe and then resubscribe if there's a new email. Other email systems do this. Opt-in confirmation could still be sent to new email but keep the same record. Thank you.