|Type||Single Opt-In||Double Opt-In|
More subscribers are added to your list, since there is no confirmation. They are added instantly to your list the minute they enter their email address and submit the form.
Higher quality subscribers and leads since they need to undergo a “2 step process” — enter email into form and click confirmation link — before they’re added to your list. Better deliverability, open, click, bounce, and spam rates.
Lower quality subscribers and leads since it’s only a “1 step process”. Deliverability, open, click, bounce, and spam rates are not as good as double opt-in.
Less subscribers are added to your list because they have to complete the “2 step process”. Stats vary, but you can expect around 60% - 80% of people confirm their subscription, which means if 1000 people enter their email address, only 600 – 800 are added to your list.