How to parse an email address

[Hornstar]

I wasnt sure where to ask this but I know people here will be able to help, so here it goes.

I am trying to parse the email address when people register into a form on the registeration confirmation page.

This is the info I was given.

<iframe frameborder="0" style="width: 650px; height: 500px; border: 0;"
src="http://www.bravenet.com/c/coreg/iframe.php?partner=gamerzneeds&email="></iframe>

If you are on a page that has the email available to you, just hop in to
php and fill it in as part of the url. So rather than having "email="
as above, you would have "email=<?= $email ?>", assuming that $email
contains the email address.

I tried <iframe frameborder="0" style="width: 650px; height: 500px; border: 0;"
src="http://www.bravenet.com/c/coreg/iframe.php?partner=gamerzneeds&email=<?= $email ?>"></iframe>

But it didnt seem to work. Is this because I did it on the page after they entered their email address? or because the code is wrong?

Thanks and hopefully someone will know the answer to this question.