Consent Sync for Klaviyo, Segment, Braze and Brevo: Keep Email Tracking Consent in Step With Your CMP

A subscriber agrees to email open tracking when they sign up. A few weeks later they open your website's privacy settings and withdraw it. Your consent management platform (CMP) records the change. Your email service provider (ESP), the system that actually inserts the tracking pixel, never hears about it.

Consent Sync for Klaviyo, Segment, Braze and Brevo: Keep Email Tracking Consent in Step With Your CMP

That gap is common because the CMP runs in the visitor's browser while the ESP decides what to track per contact on its own servers. Unless something connects the two, a withdrawal stays in the CMP and the tracking continues.

Why consent has to reach the ESP

Under the GDPR, withdrawing consent must be as easy as giving it (Article 7(3)), and processing based on that consent has to stop once it's withdrawn. If the ESP keeps adding the pixel, the withdrawal has no practical effect. For privacy teams that's a compliance issue. For marketing teams it means reports include people who said no.

Most teams solve this with a custom integration per tool, which someone then has to maintain every time the site or the ESP changes.

What UniConsent now does

When the email open tracking consent changes, either in the consent banner or through your own sign-up form, UniConsent checks which email platforms are loaded on the page and updates the visitor's profile:

Email platform	Where the choice is stored	Needs the email on the page
Klaviyo	Profile property email_open_tracking	Yes
Segment	Trait email_open_tracking	No
Braze	Custom attribute email_open_tracking	No
Brevo	Contact attribute EMAIL_OPEN_TRACKING	Yes

Each platform is only called if its script is present on your site, so there's nothing to install on the ESP side.

Setting it up in your ESP

Marketing ops teams use the property to control tracking, typically with a segment or audience such as "email_open_tracking is true" for sends where open tracking is enabled, and another for everyone else. How you switch the pixel off differs between ESPs: some allow it per campaign, others only per account or not at all, so check your platform's settings before you plan the rollout.

For Brevo, create a Boolean contact attribute named EMAIL_OPEN_TRACKING first, because Brevo ignores attributes that don't exist.

Product considerations

The sync covers changes made on your website, where the ESP's script is running. Choices made inside a mobile app reach the ESP through the app's own ESP SDK. UniConsent's iOS, Android, Flutter and React Native SDKs expose the current choice so your app can pass it on.

At sign-up, the most reliable approach is still to send the checkbox value to the ESP together with the subscription itself. The automatic sync then keeps that value current as people change their minds.

For developers

The sync is built into the UniConsent JavaScript SDK and needs no extra code once the email_open_tracking custom purpose exists. Klaviyo and Brevo identify contacts by email, so push the address as a user ID through _unicData when your form is submitted. UniConsent keeps only an email_hash in its own records, and uses the address in the browser only to identify the contact to the ESP.

For any other platform, listen for the uniconsent:update event and read UNIC_CP_email_open_tracking from the event detail. Details are in the email open tracking consent guide.

Audit trail

Every change is also written to the UniConsent Consent DB with the subscriber's hashed email, so you can show when consent was given and withdrawn independently of what the ESP stores.

Start with how to ask for email tracking pixel consent.

About UniConsent

UniConsent is a consent management platform (CMP) for websites and apps, supporting GDPR, the UK GDPR, IAB TCF, US state privacy laws and more. Get started for free.