How to customise customers emails

[khime]

Hi, I am asking if anybody knows how to modify the emails sent to the customers via oscommerce or at least know which files to modify

 

Basically I want to add a message

 

This email does not act as a contract between XXXX and yourself. The contract will not be formed until we charge your credit / debit card at the point of despatch of the goods. We will send you an email to let you know the goods have been despatched to you, and your offer has been accepted.

 

As we have had a problem with incorrect pricing and the customer saying that we accepted the order even though it was placed online and the email was sent automatically. I think this message will prevent customers from complaining when the item is obviously underpriced.