checkbox to "pass details on"

Hi,
At the bottom of my form I need to have a "please tick this box if you dont want ..." . What is the easiest way to do this, and to get the results displayed in the email? (whether its a tick or not)....

Many thanks

Here is the form: http://opwall.com/get-involved/making-a-booking/research-assistants-and-dissertation-students-for-2013/

About half way down is a checkbox with the text : Please note we will be passing on your.....

At the moment, that is just a checkbox field, the field label is the text displayed, and the checkbox label is left blank., with a value of 'checked'. I need this to be empty by default, which it is but also to display in the received email if it is checked or not. I was just wondering if there was a more specific or better way of doing this?

Theres also one down the bottom, although its not so important if this comes through in the email or not (it just has to be ticked in order to send)

I thought it might have been a standard/advanced field..??

Thanks