[Receiptful] - Don't send receipt for virtual products.

receiptful.php

<?php

if ( function_exists( 'Receiptful' ) ) :
    add_action('receiptful_order_status_processing_notification', 'receiptful_no_receipt_virtual_orders', 5, 1);
    function receiptful_no_receipt_virtual_orders($order_id)
    {
        $order = new WC_Order($order_id);
        if (count($order->get_items()) > 0) {
            foreach ($order->get_items() as $item) {
                if ('line_item' == $item['type']) {
                    $_product = $order->get_product_from_item($item);
                    if ($_product->is_virtual()) :
                        remove_action('receiptful_order_status_processing_notification', array(WC()->mailer->emails['WC_Email_Customer_Completed_Order'], 'trigger'));
                    endif;
                }
            }
        }
    }
endif;

?>