controlling the title through the url-link

In my site I have a special page containingjust the contact form. Then I want to activate the contact form from a post. Of course using a html-link. Every post that will use this contact form can be about different things that the user are interested in. If he is interested in a certain post, he has to register through thos form. And to know what post this email come from I want to have the title set that identify this post maybe the title of the post.
How do I do with the link in the post and how could I copy this id to the contactforms title?

Hope it could be simple, at least that it is possible.