In June 2021, Apple announced the rollout of iOS 15 starting in September 2021. This announcement came not long after iOS 14 caused waves in the digital advertising space for its impact on IDFA and mobile tracking. The iOS 15 update caused more waves, targeting user email and following a larger trend of tech giants prioritizing data privacy. The impact will severely limit the effectiveness of one of our key email marketing metrics: open rates. Read on to learn the ins and outs of the iOS 15 update, why it’s causing such a radical change in email marketing, and what you can do to adjust!



iOS 15 features three major updates which will limit individual tracking and impacts the ways marketers track email metrics:

      • Private Relay, which acts as a VPN to hide a user’s IP address online.
      • Hide My Email, which allows users to mask their email addresses.
      • Mail Privacy Protection, which will severely inflate open rates.

With Private Relay, users can automatically hide their IP address while browsing with Safari. This will reduce the effectiveness of third-party data, limiting email marketers’ ability to send geographically targeted content. Hide My Email works similarly, allowing users to mask their email addresses when interacting with businesses. If you have gated content, for example, a user with Hide My Email will be able to use a fake address to access that content, filling your subscriber list with dead email addresses. Fortunately, since both Private Relay and Hide My Email are included with iCloud+, a subscription service for extra data privacy protection, their impact on the marketing space will be much smaller.

The biggest disrupter coming from iOS 15 is the free Mail Privacy Protection feature, which boosts users’ mail privacy by masking IP addresses and blocking third parties from tracking email opens or other IP data. How exactly will this impact open rates? Open rates are tracked through a small invisible image embedded in the code of your email, which loads when upon opening. The loading of that image is what tells the sender the email was opened. Mail Privacy Protection pre-loads those images when the email is received, instead of when it’s opened, making it impossible to tell if Apple users are actually opening your emails.



Open rates have traditionally been the primary metric for measuring the effectiveness of your subject line or the engagement of your subscribers. Since anywhere between 30-50% of your user base is using Apple Mail, marketers should prepare to see their open rates inflate significantly. Unfortunately, this means open rates will no longer be a useful measure of success or tool for segmentation. For example, if your email marketing strategy involves sending a follow-up to users depending on if they engaged with your first email, you won’t be able to reliably segment your audience into “opened” or “unopened.” In that same vein, it will become much more difficult to use A/B testing for subject lines.

Additionally, the iOS 15 update will make it harder to scrub inactive users from your subscriber list. Because Mail Privacy Protection will reduce engagement accuracy, it will be near-impossible to tell which users are truly inactive.



The good news is the adoption of iOS 15 remains at 31.89%, according to MixPanel, which means there’s still time to adjust your email marketing strategy. There are plenty of useful metrics to determine what’s working and what isn’t, depending on your goals. Those metrics include:

      • Click-through rate
      • Survey data
      • Event signups
      • Shares on social media

If you’d like to get a closer estimate of your open rate, you can contact your ESP to help you segment out your Apple mail users. Once you have a percentage of Apple users in hand, run your inflated open rate through an iOS 15 calculator like the one found on to get your estimated open rate.

Another tactic is to collect more specific data from your users earlier in their customer journey. Get creative! Design landing pages that ask which mobile platform customers are using or implement surveys to collect personal data.

Despite the iOS 15 update, email continues to be one of the most effective ways of communicating with your audience. However, we can expect tech companies to continue implementing updates to protect user data privacy and with Google’s impending cookie-pocolypse, marketers need to remain adaptable. Stay up to date with changes in the data tracking sphere and update your marketing strategy accordingly! Need help navigating these changes? Contact the GROWL team today!

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