The problem
If a contact who already exists (unsubscribed) in your database signs up via your newsletter form, the sign-up fails – the error “email already exists” appears. Without further configuration, the existing record is not updated and the contact remains unsubscribed.
For exactly this case, there is a dedicated trigger in the automation of your email list that lets you resend the double opt-in confirmation. This provides unsubscribed contacts with a clean resubscribe path.
Setting up the resubscribe automation
In the left sidebar, go to Data Platform > Automations and open the email list that your newsletter form is linked to.
Open the Workflow Builder and click + Create.
Select the trigger "When user exists in the database". This trigger applies when an email address entered in the form already exists in the list, so the sign-up is intercepted with "email already exists").
Add the service Send Email and select your confirmation email – following the same structure as in 🔎 Double opt-in automation.
Add the Subscribe service in combination with On link click, so that the contact's status only changes to "Subscribed" after the email has been confirmed.
Connect the fields and save the workflow.
Result: When an unsubscribed contact fills out the form again, they receive the confirmation email. After clicking the confirmation link, the contact is properly re-subscribed via double opt-in.
Alternative: “Allow updates to collection”
In the form settings, you will find the Allow updates to collection option. When it is enabled, an existing record is automatically overwritten with the latest form input upon resubmission, instead of showing the "email already exists" error.
💡 Note: This is not a resubscribe in the sense of the double opt-in procedure: the unsubscribe status is not verified via a confirmation email here; instead, this is a single opt-in update of the data. The option is disabled by default. For (re-)subscribing to the newsletter, we recommend the resubscribe automation above.