The email that a customer gets sent after they have purchased something through Paypal... is it possible to edit the text that is sent out?

Well after investigation, it appears that you can't...

 

But you can use IPN (Instant Payment Notification) to send out a separate email with whatever you want in it.

You can e-mail when amendments to, ah, you can email your content to include some random variable, so that procedures are in place to control these variables, can achieve this matter to achieve the purpose of the success of e-mail.