Safari blocks identity resolution: a setback for Belgian businesses' ad retargeting

On 19 October 2026, Apple confirmed in an official WebKit post that Safari now blocks identity resolution, a technique that turned an email address into a permanent advertising identifier. The measure applies with iOS, iPadOS, macOS and visionOS 27, rolled out since 14 September. For a Belgian business running ad retargeting, a share of its Safari audience becomes unreachable overnight.

1. What Apple is actually blocking

Until now, some ad vendors quietly captured the email address typed during a login or newsletter sign-up. That address was turned into a unique, persistent identifier, handed back to the page to recognise the visitor across different sites. According to WebKit, unsubscribing from a newsletter did not remove that identifier at the third party.

Safari 27 now blocks network access to this infrastructure at domain level, preventing vendors from working around the block by reshaping their requests. Companies such as ID5, LiveRamp, Permutive and Audigent are affected, according to PPC Land.

2. Why it matters for a Belgian business

A business running ad retargeting on Facebook, Instagram or programmatic platforms often relies on these identifiers to recognise a website visitor and show them an ad later. With Safari 27, that recognition no longer works for part of the traffic, whether the visitor is logged in or not.

Belgium has a significant share of iPhone and Mac users, hence Safari browser traffic. Audiences built from an email-based identifier lose precision, and ad auctions on that traffic become less reliable.

3. What still works

Apple specifies that personalisation carried out directly by the visited site is not affected: a site can still recognise a user logged into their own account. It is the cross-site matching of that information by a third party that is targeted.

Retargeting therefore remains possible through a site's own data (newsletter, customer account, first-party cart tracking), but not through third-party databases shared between advertisers.

4. A trend dating back to 2020

Apple frames this measure as a continuation of the third-party cookie block launched in Safari in March 2020. WebKit acknowledges a cat-and-mouse logic with the advertising industry: every workaround found by identity vendors eventually gets closed.

The AI lens, humans first

An analytics tool can spot within hours the drop in match rate on Safari traffic and flag which ad audiences are losing volume. But deciding whether to shift budget toward first-party data (newsletter, customer account) or other channels remains a human strategic call, depending on each business's model. AI executes. Expertise decides, and keeps watch.