I need to send a copy of the order email to a particular email address every time an success order was placed. Is there way to configure this in magento without modifying or rewriting the sales order class ?
In your Magento Admin Panel, go to System > Configuration and in left tabs find Sales
Under sales select 'Sales Emails' , there in every tab and for every email type: order or invoice or shipment, there is option: Send Order Email Copy To write your desired email address here.
Select "Send Order Email Copy Method" if you want to send it as separate email or as BCC.
Magento Admin -> System -> Configuration -> Sales -> Sales Emails -> Order -> Send Order Email Copy To