When creating a form, you have the option to redirect the user to a different page after they have submitted the form:

In addition to redirecting, you can also have some data about the new subscriber sent along in a query string. If you check the “Send subscriber data to post-submission page” box, you will get something like this URL:

“http://google.com?drip_email=example%40gmail.com&drip_subscriber_id=gtumu4zihebvms5sdy6o”

You can then use your new subscribers email to customize your page with a response. In addition, you can use the subscriber_id to make API calls and get even more data about your new subscriber.

This option is also available for the post-confirmation redirect page, and will yield the same results in the query string.