/* $sendTo = array( array( 'email' => $this->getCustomerEmail(), 'name' => $customerName ) ); */

    if ($copyTo && $copyMethod == 'copy') {
        foreach ($copyTo as $email) {
            $sendTo[] = array(
                'email' => $email,
                'name'  => null
            );
        }
    }

http://stackoverflow.com/questions/4647648/magento-how-to-send-order-emails-only-to-the-admin-not-to-customer/4667909#4667909

Overlook sending of emails in Mage_Sales_Model_Order->sendNewOrderEmail(), remove sending to customer from there.

(around line 872)

prevent cutomer from getting order emails

magento

PHP