WooCommerce Extra E-mail Notification

gistfile1.txt

add_filter( 'woocommerce_email_headers', 'add_bcc_to_wc_admin_new_order', 10, 3 );

function add_bcc_to_wc_admin_new_order( $headers = '', $id = '', $wc_email = array() ) {
    if ( $id == 'customer_completed_order' ) {
        $headers .= "Bcc: [email protected]\r\n"; // replace [email protected] with your email
    }
    return $headers;
}