The hidden page
You found the hidden page. In 2011 this is where the Double Subscribe script lived, the one that moved a large share of your subscribers onto a second list off a single yes.
The code is gone, and you do not want it. It was PHP glued to an autoresponder API that has been dead for over a decade.
What it did is trivial to rebuild, because every modern email platform does it with a tag and an automation. Someone confirms the first list. You put one relevant yes in front of them at that exact moment. The tag fires and they land on the second list.
That timing is the whole trick, and it is why the method still converts. A person who just said yes is far more likely to say yes again than the same person is tomorrow. Page 45 of the book walks through why, with the example.
Joe Lavery · Modern Creator, LLC
Response Dynamite · Third Edition, 2011 · Free to read