It's OK to require e-delivery as a feature of new accounts, but what you describe isn't across the board. In spite of your "requirement" and the customer's agreement (on paper?) to the "requirement", by going home and doing nothing, the customer will get paper documents. If I'm the customer who confirms my consent online, then when I learn that others got paper (which is what I really wanted), I won't be happy.
Operationally, you're asking for higher cost and more errors if you plan to review and reset the delivery option for each new account.