Put it in an iframe, then. No URL change, no page change. In any case, once the page has changed the URL visible to the user it's already too late. Their data

Put it in an iframe, then. No URL change, no page change. In any case, once the page has changed the URL visible to the user it's already too late. Their data is sent. I guess it's nice that they are informed that something happened but not really. And that unknown server could easily redirect the user straight back to the site they were on, so the user would only see a flash on their screen.