To prevent customers with an existing Core-portal basic account from registering again, you can enable the Check new registrations on existing e-mail address setting.
This setting ensures that if a customer tries to create a new account with an e-mail address that is already linked to an existing account, the registration will not be accepted. Instead, a message will be displayed informing the customer that the e-mail address is already linked to an existing account and that they can log in using that account. This ensures that no duplicate accounts are created.
Follow the steps below to enable the setting.
1. Log in to the CMS.
2. Go to Core-portal basics> Settings.
3. Click the Start page tab and enable the setting Check new registrations on existing e-mail address.
4. Save the change and the setting is now active.