I am not certain the signup I have is the same kind of double opt-in you need, but you are welcome to take a look and if it’s what you need, I will give you the source code and explain how to apply it to the exported output of a blocs project. To see how it works, you will have to use it to signup. This is not a trick to get you to signup. The link below is a onetime pass to our test system. Somebody besides you might use it before you see this. If this link does not let you in, just let me know and I will reset it. I’d ask people not you to please refrain from using this one time pass. I just don’t want to have a lot of extra access to our test environment.
When you you get in, you will see a link for registering in the upper right. If you click that, you will get a form for registering on the test site. Once you submit the form, you will get a an email at the address you registered. That email will contain a link for confirming you email. When you click that confirmation link, it completes your double opt in.
If you like how that works, I will give you the code and the mysql table that supports this, and show you how to tie to to blocs. That is exactly what we did.
One time pass for the OP only