Currently, we support double opt-in through automation only. Here’s how you do that:
Though double opt-in as an optional feature might be coming back in the future.
If you’re wondering what’s the difference between single opt-in and double opt-in forms? The difference is that with the double opt-in form, the subscriber has to prove the email address exists by clicking a link they get with an email while the single opt-in form instantly adds the subscriber to your subscriber list. The downside of double opt-in forms is that you lose a significant portion of new subscribers.
An example of a confirmation email, using the double opt-in method: