What does Safari 27 block?

Network access to third parties that collect email addresses at login or newsletter sign-up and turn them into persistent tracking IDs, according to WebKit's October 19, 2026 post.

Does it name the blocked companies?

No. WebKit names no company and publishes no list of blocked domains.

Does this affect Amazon Ads?

WebKit does not say. Ads shown and measured inside Amazon rely on Amazon's own sign-in. Off-Amazon retargeting and audience tools that match by email are the ones to check with your vendor.

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Safari 27 blocks email tracking IDs - what it means for ad spend

Matthieu

October 21, 2026

4 min

Summarize with AI

CTO at Nova Analytics

Matthieu oversees product development at Nova Analytics, creating innovative tools that help Amazon sellers make smarter, data-driven decisions to grow their business.

Quick Summary

•WebKit confirmed on October 19, 2026 that Safari 27 blocks email-to-ID trackers
•The block covers iOS, iPadOS, macOS and visionOS 27
•No company or domain list is named
•Check off-Amazon retargeting and audience tools before Black Friday

Nova surfaces every Amazon fee, refund, and margin shift in your live P&L, across 23 marketplaces. Explore the live P&L

Apple's Safari 27 blocks companies that turn the email address you type on a website into a tracking ID. The WebKit team confirmed it on October 19, 2026, in a post titled Blocking identity resolution infrastructure. For sellers who pay for off-Amazon retargeting or audience matching, part of that spend may now reach Safari shoppers without an identifier.

What happened

WebKit describes the method it calls identity resolution. A third party on the page picks up your email when you log in or sign up for a newsletter, sends it to its servers, creates a tracking ID tied to that address and returns it to the site. Logging out or unsubscribing does not remove the ID, as Help Net Security summarizes.

Safari and WebKit in the iOS, iPadOS, macOS and visionOS 27 releases now block network access to those third parties. The post names no company and publishes no list, as PPC Land notes. Safari already blocked cross-site cookies six years ago; this closes the method that replaced them.

Why it matters

Many brands send Meta, Google or programmatic traffic to Amazon listings or to their own site. Tools that recognize the same shopper across sites by email are part of how those audiences are built and measured. If a vendor relies on this method, results on iPhones and Macs can drop with no error message, just weaker numbers. Ads shown and measured inside Amazon run on Amazon's own sign-in, and WebKit's post does not mention them.

What to check before Black Friday

Ask each ad vendor whether it matches audiences by turning emails into IDs in the browser
Compare retargeting and audience results on Safari against Chrome from now through Black Friday
Check that your own email list and customer data are still sent through server-side or first-party tools
Read off-Amazon campaign results by sales on Amazon, not only by platform-reported conversions

For the live view of what happens on Amazon during the peak, read how to track Amazon Black Friday sales live.

Measuring by sales, not by pixels

Nova reads your orders from Amazon as they happen, so you can see whether an off-Amazon campaign moved sales on the day it ran, without depending on browser tracking. See Live Orders Stream.

Verified Sources

All information verified from official Amazon sources and trusted industry analysts as of publication date.

Safari 27 blocks email tracking IDs - what it means for ad spend

Quick Summary

What happened

Why it matters

What to check before Black Friday

Measuring by sales, not by pixels

Verified Sources

Ask Claude about your Amazon data

Ask Claude about your Amazon data

What happened

Why it matters

What to check before Black Friday

Measuring by sales, not by pixels

Frequently Asked Questions

What does Safari 27 block?

Which devices are covered?

Does it name the blocked companies?

Does this affect Amazon Ads?

Frequently Asked Questions

What does Safari 27 block?

Which devices are covered?

Does it name the blocked companies?

Does this affect Amazon Ads?