Upon completion of an order, Ubercart sends an e-mail message to the customer with an invoice. The message is detailed but fairly generic. There are three ways to customize it for a particular store.
The invoice is generated from a theme template. The customer invoice template file is in
sites/all/modules/ubercart/uc_order/templates/uc-order--customer.tpl.php. This template file contains HTML code and PHP code that generates HTML. The PHP code has a wide variety of data available to it that it can use to generate the HTML for the invoice e-mail. Read the comments of that file for more details.
It is not a good idea to modify the template file directly. If that is done, the customizations are lost when Ubercart is updated. However, registering a copy of the template is tricky.
Preparing a theme directory
All of the methods listed below require that you put a template file into your theme directory. (See the Theming Guide for information about themes.) However, you should not put the template file into any of the standard distributed themes, including those themes built-in to Drupal (like Bartik). You may lose it when you update your theme or Drupal core!Read more