Although FastSpring does not directly accept email, mail, or faxed purchase requests from customers, there are two ways to convert purchase requests into sales.
Option 1: Enable Purchase Orders
You can enable purchase orders in your FastSpring store by going to SpringBoard's Store Home » Store Settings » Payment Methods. You may only want to accept purchase orders for specific customers; in this case you should choose Enabled via URL and add ?option=po to the end of the URL you send the customer. For more detailed information, see Integrate Purchase Orders in Your Store.
Option 2: Use Order Creator
When you can work out a deal with your customer in advance, using SpringBoard's Order Creator, you can create an order on behalf of the customer with the details of the order (specific products, quantities of each product, and applicable discounts, including volume (“tiered”) discounts) and then provide the customer a URL for purchase completion.
To create an order, go to SpringBoard's Store Home » Order Creator.