Apple introduced new privacy features at its annual Worldwide Developer Conference last week, and the impact they will have on email marketing is nothing short of an earthquake. The Mail app in iOS 15, iPadOS 15, and macOS Monterey will now allow users to opt-in what they are dubbing Mail Privacy Protection, which will effectively break the open rate and all of the data that traditionally comes with it. Apples guidance for marketers sums the changes up quite succinctly:
If youve been using remote images to measure the impact of your campaigns, there are a few changes to be aware of. Since Mail content may be loaded automatically after delivery, the time of Mail viewing will no longer be correct. And since that content is loaded without revealing peoples IP addresses and without detailed headers, the location and type of device reading the Mail arent revealed. And youll see your emails as being opened, regardless of if the user read it or not. Apples privacy pillars in focus WWDC 2021
https://www.martechcube.com/apples-mail-privacy-protection-impact-on-email-advertising/