Observe Magento order change event and send email

magento-event-order-change-email.md

Observe Magento order change event and send email

XML code

<events>
    <sales_order_save_commit_after>
        <observers>
            <mail_status_change>
                <type>singleton</type>
                <class>namespace_modulename/observer</class>
                <method>statusChanged</method>
            </mail_status_change>
        </observers>
    </sales_order_save_commit_after>
</events>

##PHP code

 public function statusChanged($event)
{
    $order = $event->getOrder();
    $orderStatus = $order->getStatus();

    if ($order->getState() == Mage_Sales_Model_Order::STATE_PROCESSING){
        // TODO here
    }