Taking this a little further after it has been emailed to the new lead/customer....
If they want to approve the quote/proforma why not make a link/button available in the email which changes it to an invoice.
It then requires their credit card or if the customer has terms it approves it. Then a notification/picking ticket/packing slip is sent to fulfillment either in-house or to the outside fulfillment company.
Once fulfillment has been verified it emails the customer their product is on the way or a service/installation has been scheduled and someone will be calling, etc...
This basically rounds out the automation process.
Joe Norcott
Infusionsoft Certified Consultant