The opt-in method forms the basis for operating legally compliant email and omnichannel marketing campaigns. An opt-in method requires recipients to give a sender explicit permission to send them advertising mails. For this, the recipient:

  • actively agrees to receiving advertising emails by, for example, ticking a box, or
  • separately states that this acceptance relates solely to the receipt of advertising emails, or
  • agrees to a declaration that clearly defines the scope (Who is the advertiser? What is being advertised? How often?).

This topic provides detailed information about the opt-in procedure and the double opt-in A practice in which a recipient consents to receiving email from the sender before any promotional email is sent. Recipients receive an email with a double opt-in link, which they must click to confirm their interest. to ensure you have evidence that permission was given.

The following information is not legally binding.

Legal basis

In accordance with paragraph 7, section 2 UWG (the German Unfair Competition Act), sending advertising emails to consumers without their prior express consent is considered an unreasonable nuisance and unfair competition.

To protect consumers from receiving unwanted email (spam), legally compliant email and omnichannel marketing are based on permissions. The sender must have the consumer’s consent to receive emails (for example, newsletters).

If a recipient has given permission via an opt-in method, the sender has valid proof of consent in the event of a complaint by the recipient.

Should legal action arise, the opt-in must be demonstrable in a court of law. Precise version management of the opt-in processes is advisable for use in practice.


Transactional mails do not generally require an opt-in. For example, registration and order confirmation emails may be sent without an opt-in. However, this only applies if the transactional mails An email triggered by a recipient action (such as an order or purchase) or event (such as an anniversary). It is sent out subsequent to the event. do not contain additional advertising.

Omnichannel marketing: Separate opt-ins

In accordance with mandatory documentation requirements of data protection legislation, ensure that you collect and record a separate opt-in for each advertising medium (telephone, text message, email and so on).

The opt-in text must exclusively seek consent for sending promotional material and – as opposed to generic "general consent" for types of advertising – the text must precisely describe the promotional materials. For example, you should differentiate between a regular newsletter and a reminder message that is sent when a customer does not respond to an offer.

Validity of the permission

An opt-in may expire as established by current case law. This is generally be the case if you do not contact a recipient for over one year. The previously given consent will no longer apply if you begin contacting the recipient again after this period.

To prevent opt-ins from expiring, contact recipients regularly.

Opt-in method types

  • Double opt-in method

    Optimizely recommends the use of this opt-in method.

    The double opt-in method is a procedure in which the end user consents to receiving emails from the sender before any promotional emails are sent. Recipients receive an email with a double opt-in link, which they must click to confirm their newsletter registration.

    Their addresses are only added to the recipient list after they click the link. This method is intended to ensure that end users are not signed up for services against their will by third parties. This not only aggravates the end users but also forces them to tediously unsubscribe from the services.

    Reasons to useOptimizely Campaign to manage double opt-ins

    • The entire process is managed from a single source.
    • Almost the entire subscription process can be managed by a single system.

    By comparison, managing the process using an external system requires recipient data to be synchronized and/or imported prior to every dispatch, which is a lot more work.

  • Single opt-in method

    Optimizely does not recommend use of this opt-in method.

    Using the single opt-in method, an end user agrees to receive emails from the sender. Their email address is then entered into the recipient list. Unlike the double opt-in method, confirmation links are not sent. From a legal standpoint, the single opt-in method is not recommended because it cannot be assumed that recipients have entered their email addresses into the recipient list themselves.

  • Confirmed opt-in method

    Optimizely does not recommend the use of this opt-in method.

    In the confirmed opt-in, an end user agrees to receive emails from the sender. The recipient receives an email confirming that their data is recorded, and that they will receive newsletters by email. This method suffers the same problems as the single opt-in method, except that the recipients are directly informed that their data was entered into a recipient list.

Implementing the double opt-in method with Optimizely Campaign


With the Optimizely Campaign Opt-in processes feature you can create and manage opt-in processes and its confirmation mailings (opt-in emails). The opt-in email for the double opt-in method must include the double opt-in link. The double opt-in link refers to the confirmation page, which is provided by Optimizely or hosted by you.

Insert the {Double Opt-in Link} field function into the mailing text or add it to the HTML code, for example <p>To confirm your newsletter subscription, click the following link: <a href="{Double Opt-in Link}">Confirm subscription</a><p>.

Adapting your website

In the next step, you update your website so that the opt-in process you set up is initiated when a new recipient subscribes to the newsletter using the form. If you are using the REST API, you can add one or multiple recipients to a recipient list. You can also set up the connection using the add2 or addAll3 methods, using the SOAP API, or using the subscribe operation in the HTTP API. The opt-in process IDs required for this are available in the API overview.


Newsletter subscription

Image: Newsletter subscription

Confirmation email

Image: Confirmation email

Confirmation page

Image: Confirmation

Frequently asked questions about the double-opt-in method

1. How do I explain the additional steps to new subscribers when they sign up for the newsletter?

  • Information. After new subscribers enter their information, clearly inform them that an additional step is required to activate the newsletter subscription ("We have added your email address to our list. To activate ... "). Explain why this step is necessary. For example, "to prevent other people from subscribing using your email address" or "to validate your email address".
  • Link. Instruct recipients to activate their subscription after entering their information. If possible, provide a link to their mailbox for activating the subscription. You can use the domain parts of the email address to determine which email provider the recipient is using and to create a link to the specific service. Example: If the new subscriber has an xxxx@example.com address, then you can display a "Go to my email inbox" link that takes them to the login page at www.example.com.
  • When to send the confirmation email. You should send the confirmation email as soon as possible after the sign up, so it can be activated quickly. The recipient may otherwise forget the reason for the confirmation email or lose interest in the newsletter.

2. What should I be aware of when setting up the activation email?

  • Subject. Ensure that your activation email has a meaningful subject line that directly prompts the user to take action. For example, "Please confirm your email address".
  • Sender.The sender name is often the first thing that a person sees and should be recognizable. You should use a consistent sender name for emails, including the activation email. Give your potential subscriber an option to reply to the activation email (avoid using a noreply@...email address).
  • Presentation. The activation email should avoid using large blocks of text and complicated layouts. Your recipient needs to click the confirmation link. Help them by providing concise and accurate instructions along with a clearly visible confirmation link.
  • Spam suspicion. Inform new subscribers that emails from new and previously unknown senders may land in their spam/junk mail or unknown mail folders. If the recipient cannot find the confirmation email, they should check these folders.

3. What problems can arise when using the confirmation link in an activation email?

  • Short length. Make sure that the confirmation link is not too long. Otherwise, there is a danger that it may get broken across two lines and no longer work. In case this happens, you should offer a solution to your subscribers, for example, "If the link does not work, copy both lines into the address bar of your browser." You should further ensure that the confirmation link stands out from the other text in the message, even if the email preview area is small.
  • Correct link. A further potential source of problems is a confirmation link that does not work. This can happen if the link contains a special character, which causes Outlook or Thunderbird to incorrectly highlight it and thus send the user to a blank page. Another frequent link problem is forgetting to use the HTML anchor tag properly. Check that the confirmation link is correct.

4. How can I avoid any possible problems with the sign up process?

  • Address book entry. Tell new subscribers to add your email sender address to their personal address book or list of secure senders. You can say something like "To ensure that you receive our newsletter...". This will ideally be supplemented with a link to instructions for common email programs and webmail providers to help with this step. You can also provide a vCard that can be used with some email programs to add your contact data to the address book with a single mouse click.
  • Help / contact options. Give the user options for providing feedback or contacting you (email address, chat, free phone number, "not working" button) in case of problems with registration or confirmation. This can also be an important feedback channel for identifying problems or areas for improvement in the process. A more elegant solution is to provide contact information for a personal adviser or customer support representative , if this would be appropriate or possible.
  • Resending. Provide the recipient the option of having the activation email resent in the event that it has not arrived within the first few minutes or the recipient is unable to find it.

With the help of a special function you can automatically send the last newsletter sent to newly subscribed recipients as soon as they have gone through the opt-in process. For more information, see Scheduled jobs.