September 2021 saw Apple Mail release Mail Privacy Protection (MPP), so for Apple device users who opt in, email marketers will lose the ability to accurately measure both whether an email has been opened and where a subscriber is. What does this mean for email marketing metrics?

Apple privacy upgrades

Apple has released Apple iOS 15 and macOS Monterey versions, giving Apple Mail users the option to enable new privacy protection. This release has been available to Apple users since September 2021 and so far the impacts on email marketing have been minimal. However, there are some factors companies can consider to be well-prepared for these privacy changes.

Understand email marketing metrics

Email marketing software programs report on standard metrics, such as:

  • open rate (the measure of how many emails recipients opened divided by the total number of emails sent)
  • click rate (the measure of the number of clicks on links in the email divided by the total number of emails sent)
  • click-to-open rate, or CTOR (the measure of the number of clicks on links in the email divided by the total number of people who opened the email).


As marketers, our aim is to increase these three rates by creating compelling subject lines and offers. However, due to the recent Apple MPP launch, open rate and CTOR could start to return artificially higher rates for subscribers using Apple devices.

How does it work?

An email is deemed to be ‘open’ when the graphics in the email are downloaded to a subscriber’s mobile phone, tablet or computer. The changes put in place by Apple mean that the images are downloaded when the inbox receives the email, not when someone opens it.


If the email-sending software – for example, HubSpot, Campaign Monitor, Mailchimp or Klaviyo – records this image download as an ‘open’ (and it will), then the open rates will be artificially higher than they were before these changes. Impacts to CTOR and other metrics that rely on open rate will see similar false increases.


MPP opt-in users will also suppress their IP address. As a result, their location will be less reliable.

What can email marketers do?

Although these changes have some impact on reporting, they also provide email marketers with an opportunity to look at metrics other than open rate and CTOR when measuring the success of email campaigns. These other metrics include:


  • revenue – the bottom line for ecommerce emails. If your email software integrates with your ecommerce website, this metric is the best for measuring a sales campaign’s success
  • click rate – for non-sales EDMs when marketers are more interested in measuring engagement, the click rate is the premier metric, and MPP does not impact the collection of click rate data
  • segmentation – if you are using segments based on metrics affected by MPP, consider changing these segmentation rules to use click rate instead. Data on Apple users in email software is considered unreliable, so it is not recommended to segment out Apple users on this basis. In many cases, Apple users may not have opted in to the MPP, so this will not affect their measure of opens
  • A/B testing – with luck, this should be a random mix of Apple and non-Apple device users, so we expect few impacts. If you do notice some A/B testing anomalies, you could consider changing the A/B test goal from increase open rate to increase click rate
  • automation – check your email automation triggers for any that opens trigger. It may be prudent to change your trigger condition to one of the options that includes ‘click’ – for example, link was clicked or specific link was clicked.


Although it is early days to evaluate MPP and the impacts on email marketing, there are certainly potential pitfalls you can avoid with a little bit of additional planning. Here at Mastermind, we will continue to monitor the changes and will update you on the material changes we see. We don’t predict any drastic fall in the importance of email to drive conversions on your website and revenue growth for your B2C or B2B business.


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