How to stop Order Acknowledgements from repeating

Ok this has got to be a simple check box but I'm going crazy trying to find it......we have many customers setup to get order acknowledgments via email, with the "Print/Acknowledge Sales Orders" task. The problem we're having is that once a customer is emailed an acknowledgement, every time we reprint the Sales Order from the main Enter Sales Orders and Quotes task, another email acknowledgment goes out to the customer.


Anybody know where to change this setting or how to ensure only one copy of an acknowledgement ever goes out?