• by Rachel Hazelwood , Op-Ed Contributor, August 25, 2025

If you're still judging email performance by open rates, it's time to catch up. Apple’s iOS 15 put open rates on life support, and iOS 18 pulled the plug.

With Apple devices responsible for nearly half of all email engagement, any change to the inbox experience has ripple effects.

iOS 18 has made it clear: email opens are no longer a reliable measure of success. Between AI summaries, tabbed inboxes, and Digest View, marketers are flying blind if they’re still optimizing for opens. The data doesn’t lie. The decline is real. It’s time to evolve.

A Look Back at What Happened

Marketers were watching closely when Apple launched iOS 18 in September 2024, and for good reason. The update introduced AI-generated summaries that display information directly in the inbox, making pre-header text nearly obsolete. Users can grasp the essentials without clicking, weakening opens as an engagement signal. If the pre-read delivers, why bother opening?

Email is also now sorted into tabs — Primary, Promotions, Transactions, Updates — mirroring Gmail’s model, and making it harder to stand out. If your message lands in Promotions, good luck competing for attention.

Then there's Digest View. Apple bundles emails from the same sender into a scrollable stack. Multiple messages may appear opened even if the user doesn’t act. Early results show a 23% spike in auto-opens and up to a 25% drop in click-through rates on iOS devices. You’re not just getting less accurate data. You’re losing exposure.

The impact to email opens was substantial. Our post-iOS 18 analysis shows that email open volume for Apple devices declined by 35% across the brands we support—continuing the metric’s degradation as an optimization signal and highlighting how misleading opens have become. 

What We’ve Done to Win Since

To stay competitive, adopted three core tactics:

1. Enhance Content Relevance
   You’re competing for attention so subject lines and email content must deliver value fast. Brands doing this have seen mobile CTR improve by 12–18% in A/B tests.2 

2. Shift Measurement Strategies
   Post-click measures offer more actionable insights. Teams focused on these optimize performance faster than those relying on opens.

3. Get Real About Personalization
   Most ESPs now support dynamic content built on real-time behavior. Stitch together signals like browsing, cart status, loyalty tier, or local inventory, and serve modular content that updates at open.

Identity resolution tools have made this an easy lift. From email segmentation enriched with attributes like in-market behavior or product affinity, to comprehensive cross-channel attribution at the audience level, the right identity, and personalization technologies help activate smarter campaigns.

Reframing Email Engagement

Apple’s changes aren't just disruptive. They're a catalyst for smarter, more intentional email engagement strategies.

Best practice is to optimize for engagement but for some the shift away from opens is still in progress. Let’s look at an email marketing scenario with two brands to reframe to opportunity. 

Brand A tracks opens, not outcomes. Brand B optimizes for action. They use generative AI to test 10 subject line variants simultaneously. Email CTR jumps from 2.7% to 4.3%, aligning with recent benchmarks. Product modules update dynamically at open, boosting revenue per email by 2.2×—mirroring findings from outcome-focused brands. With smarter segmentation and downstream measurement, Brand B improves efficiency by 5–15%.

Metrics reflecting meaningful behavior matter most now: like CTR, website engagement, micro-conversions, and attributed revenue. Email’s influence across the customer journey is also critical, requiring broader lifecycle metrics.

How do you act on that? Start by joining datasets across platforms and prioritize tracking post-click actions for a more complete view of performance. Understand the relationship between email sends, engagement and sales at a customer level with measurement models like RFM/E (recency, frequency, monetary value, engagement) that layer onsite behavior into email cohort analysis. Then, leverage 1:1 multi-touch attribution to understand how email supports touchpoints such as programmatic or SMS. Armed with this analysis you’ll gain smarter sequencing and better content across the customer journey.

Success isn’t a view. It’s a visit, a scroll, a tap, a buy. That’s where real value lives—so when your email makes it through the noise, be ready.

Opens are dead. Optimize for outcomes.