Hi vaalfco,
the problem is, that everything inside the wrapper stays inside the wrapper. Even if you load a new page or “browser” a page inside that wrapper, it will stay in there.
You could try to configure the newsletter success page to open in the parent window for example. A normal has the options target=”_parent”. This should look like
<a target="_parent" href="http://url.org">link</a>
The second option is to put this inside the <head> of your newsletter page
<base target="_parent" />
If none of this helps, you’ll have to utilize Javascript. It really depends what newsletter system it is and how it works (submits the entered data).
Cheers
Frank