That's weird. I have the problem the other way around.
If someone wants to send the form back to my account, I do only receive the filled pdf - but I chose "xml" in my options. What is wrong there?
Back to topic: Malhyp, you have to create a simple button, then choose "Object" on the right, then "Control field" -> Sending an then go to the next register "Sending", type your page or mailto:firstname.lastname@example.org an choose "pdf". Thats it! (I think the names of the buttons an so on sound strange because I use the german version - so don't worry...)
If you use the Email Submit Button object it is pre-configured to submit xml. If you want to change it delete that button, drop on a standard button, make it of type submit, then on the submit tab you can determine where to submit (mailto:address) and the submission type can be set. Note that if you are using Reader you can only submit XML unless you reader extend the form.