However, with iOS 15 and macOS Monterey, Apple will be cracking down on the use of these pixels. This is through a new email privacy feature called Mail Privacy Protection that will help prevent these trackers from working and gathering data about you.
According to Apple’s description of the feature, “If you choose to turn it on, Mail Privacy Protection helps protect your privacy by preventing email senders, including Apple, from learning information about your Mail activity. When you receive an email in the Mail app, rather than downloading remote content when you open an email, Mail Privacy Protection downloads remote content in the background by default – regardless of how you do or don’t engage with the email. Apple does not learn any information about the content.”
Do note that Mail Privacy Protection will not be enabled by default. Instead, users will have to turn it on manually, but they will be prompted and notified about the new feature when they upgrade to iOS 15 or macOS Monterey.