Double opt-in refers to the process of asking people who have just filled up a webform for receiving an email newsletter to confirm their subscription. The confirmation request is made by email. If the consumer does not confirm his subscription, he is not added as a newsletter subscriber.
Double optin is usually good from an ethical point of view but not always for marketing. Indeed, a good part of newsletter form fillers are used to be indeed a subscriber after the single optin and do not notice the need to confirm. Thus, the double optin practice causes often a subscriber loss and is less common than the classic opt-in.
To reduce the potential loss of subscribers, subject line and text have to be clear about the need to confirm the subscription.
The necessary step must also be explained on the website after filling the subscription form:
It has to be noticed that in recent years, double opt-in practices are coming back due to deliverability issue. Indeed, double-optin is good for list quality and subscriber engagement and favors deliverability.
An example of double opt-in practice: