title: Send Email To The Customer On Order Complete in WooCommerce
body: <p>I am having problems with my Wordpress installation, or WooCommerce to be more specific.</p>
  
  <p>The client I've been working for the last couple of months, wants that every time a customer completes/pays an order, a custom email is sent to his email address, besides the standard order confirmation email.</p>
  
  <p>In short: <strong>I need to send a custom email to the customer when the order is completed.
  How can I do that inside the functions.php?</strong></p>
  
  <p>I tried using various hooks and functions described in the official documentation, but couldn't figure it out.</p>
  
  <p>The Wordpress version is 3.8.1, and WooCommerce is version is 2.0.20.</p>
  
  <p>Thank You in advance.</p>