Prevent duplicate subscriber entry from updating fields


We're using Campaign Monitor to power our Kids Club and having parents register their children under the one email address (for their convenience) using custom fields to capture the individual children's names.

As the registered families grow, they will want to sign up their new kids. However due to the way that Campaign Monitor enforces the uniqueness of email addresses (rather than rejecting the duplicate subscriber, it allows it to update the fields of the old entry) parents could unwillingly remove their previously registered children.

Is their a way to allow the duplicate entry or at least prevent it from updating the old entry?


Stephen, 3 years ago

Hi Cisco,

Many thanks for getting in touch and sorry to hear you're experiencing these subscription challenges here.

At present, because we use the email address value as a subscriber's unique identifier, I'm afraid it's not possible to include multiple instances of the same address within a list at this time.

While it's not possible to set a subscribe form / list to double-check for an existing subscriber prior to submission, if you have any development experience, this may be something you can achieve via our API, so please find more on this here.

Thus, just prior to the submission of your subscribe form, you could fire off an API call which checks to see whether the email address entered into your subscribe form already exists in your list.

If it doesn't, then submit the form, however if it does, you could then display a custom message, informing the subscriber that they're already subscribed, and so if they wish to update their subscription details instead, then they're able to do so via the 'Update Your Preferences' link within an existing campaign.

c15co, 3 years ago

Hi Stephen,

Thank you for your quick reply and for your help.


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