Password protect purchase orders and invoices

In this ever increasing email world, it would be beneficial to use Sage 200 to password protect PDF purchase orders and invoices etc before sending out. However, this would need to assign unique passwords to each supplier or customer account. The only option I can find is to turn on password protect within the layout, but this would assign the same password to all purchase orders. This means it is not confidential to the individual suppliers/customers and so might as well not be protected.