There are 2 ways you can stop sending to a customer about an order.
Blacklist the customer
Go to the Blacklist management page and click ‘Add New Entry’. Here you can type in one or many (one per line) Amazon seller email addresses (you know, those crazy email@example.com type addresses). After clicking ‘Create Blacklist’ your entries will be added and those customers will never get another email via ZonMaster again. Ever.
You can also blacklist a customer from their detailed info page or from one of their order detail pages.
Stop Sending For The Order
If you don’t want to go all nuclear and blacklist the customer you can also click the red ‘Stop Sending For This Order’ button on any order’s info page.