Opt-In settings determine what kind of registration to the newsletter will be used. There are two possibilities to register:
1. Single Opt-In: After a positive registration, the user receives a confirmation email and is automatically subscribed to the newsletter.
2. Double Opt-In: After a positive registration, the user receives an email, which he has to confirm. Only then will the user receive a confirmation email and is officially registered. During that registration there is the possibility of sending the latest newsletter by default to the new subscriber. That could be useful if you don't send out on a frequent base.