Thinker7 on "[Plugin: Contact Form 7] Sending url param through hidden field"

Is there is any way to insert some part of url (one param) to email, that CF7 send?
I have posts, and in each post I have link to same contact form. And I want to know from which post this contact form is filled. So I can just add one param into contact form url, and want CF7 to parse url and insert this param into email.
Is it possible?

http://wordpress.org/plugins/contact-form-7/