On looking at the calculation on the Calc_PRCemail on the OrderAck RDD. how does it come up with the email address. The reason I ask is it pulling the EMail address from the Primary Contact Sold to on the order. and if that is blank it check the CustomerMaster for email address?
You are correct.
This field uses the contact from the sales order, which is defaulted from the Customer Primary Purchasing Contact. You can change this on each order.
If you have no contact on the order, it will pull from the Customer Entry screen.