This is how the double-opt-in (DOI) process works.

The double opt-in (DOI) process is indispensable in content and email marketing. We’ll show you how to implement legally compliant registration processes using DOI.

What is the double opt-in process?

In the double opt-in process (DOI for short), the person addressed must additionally confirm their consent after providing their contact data. Anyone who has ever subscribed to a newsletter knows the procedure: after registration, an e-mail with a confirmation link follows.

Consent is not only required for sending a newsletter. In principle, it is a prerequisite for any storage and use of personal data. What exactly this involves is usually clarified in the data protection provisions.

Despite wide acceptance, many website operators still do not use the DOI procedure. This entails various risks, such as a lack of knowledge about who actually initiated the request. For this reason, I have first summarized all the important advantages and disadvantages of the double-opt-in procedure in the context of the GDPR on the basis of an article by René Kulka.

Advantages of double opt-in (DOI) methods

  • Legally compliant: Newsletter subscribers can be generated most cost-effectively and quickly via web form. Only the double opt-in process offers sufficient legal certainty here.
  • Reliability: Errors during the subscription process are noticed by the subscriber promptly. They also have the option of immediately saving the sender’s address in their contact list. This significantly increases deliverability.
  • Data hygiene: Confirmed data is most likely to be correct. Spam traps and joke entries are left out and do not contaminate the database.

Disadvantages of double opt-in methods

  • Filter effect: Confirmation e-mails do not always reach the registrant, are perceived as annoying, or are forgotten. The subscriber is not included in the distribution list and maybe annoyed.
  • Pseudo-security: The links in confirmation e-mails do not always have to be clicked by the registrant – virus scanners and spam filters sometimes follow URLs automatically to detect possible malware.
  • Setup effort: producing supplemental confirmation emails and landing pages costs money. The technology also has to do some work – for example, storing the data of registrations that have been started for a certain time – and deleting it later if necessary.


The double opt-in (DOI) process is the quasi-standard for legally valid online marketing. Its use is therefore highly recommended, even though it does have some disadvantages.