What is the difference between a double and single opt-in?

When creating a form, you can indicate whether you want to use single or double opt-in. When creating a new form, double opt-in is always enabled.

You can choose which type of opt-in you want to use. In this article, you will find an explanation of both options, including the advantages and disadvantages:

What is double opt-in?

Double opt-in consists of two steps that your contacts must go through to be added as an active contact to the list and receive emails. They not only need to sign up but also confirm the subscription. The subscription process involves not one but two (double) steps.

1. Subscription via the form.

The contact signs up via the form, receives the status 'Unconfirmed', and is also added to the list as unconfirmed. Unconfirmed contacts cannot be emailed yet and therefore do not count towards your contact limit, as they have not confirmed the sign-up yet.

2. Confirming the subscription.

Once contacts sign up (via a double opt-in process), they receive an email with a link to confirm the subscription. If they click on it, their status changes to 'Active' and they are added to the mailing list. If they do not complete this step, they remain 'Unconfirmed' and contacts cannot receive your emails.


  • Double opt-in confirms that contacts want to receive information from you and that their details are correct.
  • Contacts who complete a double opt-in are more likely to read your emails and click on links (or take other actions).
  • With double opt-in, you are likely to experience fewer spam complaints.
  • Some countries/regions require double opt-in.
  • Protects you against spam contacts.


  • Some contacts who do want to receive your emails may not complete the process, resulting in them ultimately receiving nothing.
  • The list of active contacts is likely to be shorter than when using single opt-in.

What is single opt-in?

With this form of opt-in, no confirmation of subscription is required. Once contacts sign up via a form, they are immediately added as active contacts to the list.


  • Contacts are added immediately and can receive emails right away.
  • Contacts do not need to take extra steps to make the subscription official.


  • Contacts who do not actually want to receive messages may end up on your list and may report your emails as spam, which can be detrimental to your sending reputation and email deliverability.
  • Spam contacts can be added as active contacts, which counts towards your contact limit.
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