Each list has the option for single or double opt-in. To select the opt-in method go to the subscriber list and click edit list details.
Signup & Embed Forms
Double opt-in only effects signup forms and embed codes. Your subscribers won’t be asked to confirm their email if they are added by our import feature or through the API. As always make sure you have permission to email recipient added this way.
Double Opt-in (default)
Double opt-in adds another step to the signup flow by asking the subscriber to confirm their email. By default all lists are double opt-in and require recipient confirmation.
Why choose double opt-in? Double opt-in is a great way to enhance deliverability by ensuring emails are correct and the recipient indeed wants to subscribe to your mailing list. This makes for a happier spam-free email world.
No confirmation is required.