Programmatically created order not sending order receipt email - magento

Question

When I make an order normally through the Magento store, I immediately get an email receipt. When I create an order through my custom code, No email is sent.
Here's my code:
private function _submitOrder($customer, $billing, $shipping, $products, $payment, $coupon, $finalize){
if($coupon && $this->_checkCouponValidity($coupon)){
$quote = Mage::getModel('sales/quote')->setCouponCode($coupon)->load();
}else{
$quote = Mage::getModel('sales/quote');
}
foreach($products as $item) {
if($item['qty']>0){
$product = Mage::getModel('catalog/product');
$productId = Mage::getModel('catalog/product')->getIdBySku($item['sku']);
$product->load($productId);
$quoteItem = Mage::getModel('sales/quote_item')->setProduct($product);
$quoteItem->setQuote($quote);
$quoteItem->setQty($item['qty']);
$quote->addItem($quoteItem);
}
}
$quote->getBillingAddress()
->addData($billing);
$quote->getShippingAddress()
->addData($billing)
->setShippingMethod('tablerate_bestway')
->setPaymentMethod('authorizenet')
->setCollectShippingRates(true);
$quote->setCheckoutMethod('guest')
->setCustomerId(null)
->setCustomerEmail($quote->getBillingAddress()->getEmail())
->setCustomerIsGuest(true)
->setCustomerGroupId(Mage_Customer_Model_Group::NOT_LOGGED_IN_ID);
$quote->collectTotals();
$quote->save();
$convertQuote = Mage::getSingleton('sales/convert_quote');
$quotePayment = $quote->getPayment(); // Mage_Sales_Model_Quote_Payment
$quotePayment->setMethod('authorizenet');
$order = $convertQuote->addressToOrder($quote->getShippingAddress());
if($finalize){
$orderPayment = $convertQuote->paymentToOrderPayment($quotePayment);
$order->setBillingAddress($convertQuote->addressToOrderAddress($quote->getBillingAddress()));
$order->setShippingAddress($convertQuote->addressToOrderAddress($quote->getShippingAddress()));
$order->setPayment($convertQuote->paymentToOrderPayment($quote->getPayment()));
$order->getPayment()->setCcNumber($payment['ccNumber']);
$order->getPayment()->setCcType($payment['ccType']);
$order->getPayment()->setCcExpMonth($payment['ccExpMonth']);
$order->getPayment()->setCcExpYear($payment['ccExpYear']);
$order->getPayment()->setCcLast4($payment['ccLast4']);
}
Mage::log("loop quote items");
foreach ($quote->getAllItems() as $item) {
$orderItem = $convertQuote->itemToOrderItem($item);
if ($item->getParentItem()) {
$orderItem->setParentItem($order->getItemByQuoteItemId($item->getParentItem()->getId()));
}
$order->addItem($orderItem);
}
try {
if($finalize){
$order->place();
$order->save();
if ($order->getCanSendNewEmailFlag()) {
try {
$order->sendNewOrderEmail();
} catch (Exception $e){
Mage::log($e->getMessage());
}
}
return $order;
}
else{
return $order;
}
} catch (Exception $e){
return $e->getMessage();
}
}

Answer 1

I figured out the problem.
This line:
$quote->getBillingAddress()->getEmail()
was returning nothing. I wasn't setting a shipping email when creating $billing. Whoops.