This script can be used for numerous situations when passing an email address via URL parameters.  

The script should be placed on the THANK YOU PAGE in the footer tracking area.

On the Thank You Page, you will need to create a button and link to the 3rd party follow-on passing the URL through the URL parameters with the CF Merge Tag:  #EMAIL#

So if you want to pass the email address to Google (for example purposes only), you would pass it like this:

Here is the script:

  $(function () {
  var email = localStorage.getItem("garlic:""*>") || getURLParameter("email");

  $('[href*="#EMAIL#"]').each(function () {
    var href = $(this).attr('href');
    href = href.replace(/#EMAIL#/g,email);
    $(this).attr('href', href);

Here's a quick Loom vid to show you a real life scenario of how to set this up as well:

PLEASE NOTE:   Passing the URL via the Redirect Override Feature (ON SUBMIT GOTO) through General Settings WILL NOT WORK.