How will the iOS 15 announcement affect email marketing privacy and deliverability?
Michael Ko
Co-founder & CEO, Suped
Published 16 May 2025
Updated 16 Aug 2025
8 min read
The announcement of Apple's iOS 15 brought significant changes, particularly with the introduction of Mail Privacy Protection (MPP). This feature profoundly impacts how email marketers track engagement and measure campaign performance. It masks user IP addresses and preloads email content, including tracking pixels, before a user actually opens an email, making traditional open rate metrics less reliable.
For years, email open rates have been a cornerstone for understanding subscriber engagement, segmenting audiences, and even informing spam filter decisions. The iOS 15 update challenged this established norm, leading to discussions about its implications for data accuracy, list hygiene, and overall email deliverability. The core question on many minds has been how to adapt to this new privacy-first landscape without losing crucial insights into campaign effectiveness.
Understanding these changes and their ripple effects is essential for any email marketer aiming to maintain high deliverability and effective communication with their audience. While it presents new challenges, it also pushes the industry toward more sophisticated and privacy-conscious measurement strategies.
The mail privacy protection feature
Apple's Mail Privacy Protection (MPP) is designed to give users more control over their personal data. When a user opts into MPP, Apple's servers download all email content, including tracking pixels, at the time the email is received, rather than when it is opened by the user. This pre-fetching happens regardless of whether the user actually views the email. This mechanism prevents senders from knowing if and when an email was truly opened, as well as masking the recipient's IP address, thus obscuring their location.
It's important to note that this privacy feature applies to any email account configured within the Apple Mail app on iOS, iPadOS, and macOS. This includes accounts like Gmail, Yahoo, Hotmail, and others, not just iCloud accounts. The effect is a significant inflation of reported open rates for Apple Mail users, as every email delivered appears as an open, regardless of actual user interaction. The feature stops senders from using invisible pixels to gather information.
While similar to how some mailbox providers like Gmail already cache images, Apple's implementation is more comprehensive because it automatically preloads all content and hides IP addresses. This means that even if an email lands in the spam folder, Apple's servers might still open it from a marketer's perspective, further skewing traditional metrics.
Impact on metrics and strategy
The most immediate and significant impact of iOS 15 MPP has been on the accuracy of email open rates. Marketers can no longer rely solely on this metric for critical insights into audience engagement or for A/B testing subject lines and send times. This shift necessitates a re-evaluation of how email campaign performance is measured and optimized.
Despite this, the update does not fundamentally alter how mailbox providers (like Google or Yahoo) filter incoming mail. Spam filters and inbox placement algorithms rely on a multitude of signals beyond just image opens, including real user behavior, authentication (SPF, DKIM, DMARC), spam complaints, and direct interactions. Therefore, while marketing teams need to adjust their reporting, email deliverability itself should not be directly impacted by the change in open rate data, as confirmed by providers like Hubspot.
The challenge lies in managing list hygiene and re-engagement strategies when a key metric becomes unreliable. Previously, marketers would segment or suppress subscribers based on inactivity, often defined by a lack of opens over a certain period. With MPP, these segments may appear artificially engaged. This necessitates a pivot towards alternative engagement metrics and a more holistic view of subscriber health.
Old approach
Primary metric: Reliance on open rates for engagement, segmentation, and A/B testing.
List hygiene: Identifying and removing inactive subscribers based on a lack of recorded opens.
Personalization: Using open time and location data for content optimization.
Adapting your email program
With the diminishing reliability of open rates, marketers must shift their focus to other engagement signals. Clicks are now a more critical metric than ever, providing a clearer indication of a subscriber's interest. Other forms of engagement include website visits originating from email, purchases, replies, and even social media interactions.
Regularly cleaning your email list based on a broader definition of engagement is crucial to maintaining good sender reputation and deliverability. This means removing subscribers who show no interaction across multiple touchpoints over an extended period. Focus on sending to highly engaged subscribers, as this signals to mailbox providers that your mail is wanted, which directly impacts email deliverability issues.
Furthermore, a strong emphasis on email authentication protocols, such as DMARC, SPF, and DKIM, becomes even more vital. These protocols help mailbox providers verify the authenticity of your emails, which is a key factor in determining inbox placement, regardless of open tracking. Strengthening your authentication posture contributes significantly to your domain reputation and reduces the likelihood of being flagged as spam or put on a blocklist (or blacklist).
Consider how the GDPR affects email deliverability, particularly in terms of explicit consent and maintaining legitimate interest. Without reliable open data, demonstrating ongoing engagement for compliance purposes becomes more nuanced, requiring a focus on other verifiable actions a subscriber takes.
Deliverability implications and adapting
Many email marketers have voiced concerns about the long-term effects of MPP on the health of the email ecosystem. Some argue that without reliable open data, the industry could face a race to the bottom, where senders might resort to more aggressive tactics due to a lack of clear engagement signals. However, mailbox providers generally maintain that their filtering mechanisms are sophisticated and do not rely on these specific image-based open signals.
Mailbox providers often look at a wider range of user interactions, such as clicks, replies, forwarding emails, marking as not spam, or moving emails to folders, when determining inbox placement. An email open, facilitated by a tracking pixel, was often just one data point among many, and not always the most accurate representation of true engagement. Therefore, while the metrics for marketers change, the underlying signals that determine deliverability remain largely consistent.
Warm-up strategies for new IPs or sending domains also need to adapt. Instead of relying on opens to gauge engagement during warm-up, focus shifts to observable actions like clicks and other positive interactions with your brand, both within and outside the email channel. The underlying principles of warming, such as introducing a new sending identity gradually, still apply, but the metrics used to monitor success must evolve.
This privacy-focused update from Apple highlights the ongoing trend towards greater data privacy and transparency for consumers. Email marketers must embrace this shift by focusing on delivering genuinely valuable content that drives observable engagement, rather than relying on stealthy tracking pixels. This approach builds stronger relationships with subscribers and contributes to better long-term deliverability.
Before iOS 15 MPP
Open rates: Considered a primary indicator of recipient engagement.
Segmentation: Often relied on open data to categorize active vs. inactive subscribers.
A/B testing: Subject line and send time optimizations frequently based on open rate changes.
Location targeting: IP addresses used to infer geographic location for targeted campaigns.
After iOS 15 MPP
Open rates: Inflated and less reliable for genuine engagement measurement.
A/B testing: Focus on metrics like click-through rates and conversions.
Location targeting: Less feasible or inaccurate due to masked IP addresses. Rely on self-declared user data.
Conclusion: A new era for email engagement
The iOS 15 Mail Privacy Protection update has undoubtedly shifted the landscape for email marketers. While open rates, especially for Apple Mail users, are no longer a reliable measure of actual engagement, this doesn't spell the end for email marketing or deliverability. Instead, it serves as a catalyst for a more mature and user-centric approach to email. Focusing on explicit actions such as clicks, conversions, and direct interactions provides a truer picture of subscriber interest and ensures compliance with evolving privacy expectations. By adapting measurement strategies and prioritizing valuable content, email marketers can continue to build strong relationships and achieve excellent deliverability, even in a privacy-enhanced world.
Views from the trenches
Best practices
Actively monitor engagement beyond opens, using metrics like clicks, conversions, and website activity.
Segment your audience based on diverse engagement signals to maintain list hygiene and identify truly active subscribers.
Prioritize compelling content that naturally encourages clicks and conversions, providing clear calls to action.
Regularly re-engage inactive subscribers with targeted campaigns that encourage direct interaction, then remove if no response.
Reinforce your email authentication with robust SPF, DKIM, and DMARC records to bolster sender reputation.
Common pitfalls
Continuing to rely solely on inflated open rates for campaign performance analysis and A/B testing.
Failing to adapt list hygiene practices, leading to lists full of disengaged subscribers that appear active.
Ignoring other vital engagement metrics, resulting in a skewed understanding of audience behavior.
Assuming that Mail Privacy Protection directly impacts deliverability to the spam folder, rather than just metric reporting.
Not clearly communicating the value proposition of your emails, which reduces click-through rates.
Expert tips
Use clicks as a primary indicator for warm-up audiences and re-engagement strategies.
Focus on the 'wantedness' of your mail, as mailbox providers prioritize real user interaction over pixel loads.
Explore other channels and brand interactions to inform your email strategy and identify truly engaged users.
Understand that this privacy update is a device-driven change, and mailbox providers adapt to it, but their core filtering remains robust.
Embrace the challenge to innovate and find new ways to measure engagement that are privacy-compliant and effective.
Expert view
Expert from Email Geeks says inbox placement, reputation, and spam rules do not rely on image opens. They focus on real user behavior, so email filtering will not change due to this update. Open rates have often been problematic and inaccurate.
2021-06-08 - Email Geeks
Expert view
Expert from Email Geeks says mailbox providers like Google already proxy and cache images, so "open rate tracking" was mostly unreliable. Receivers prioritize actual user interaction over how machines fetch images.
Apple Mail app on iOS, iPadOS, and macOS. This includes accounts like Gmail, Yahoo, Hotmail, and others, not just iCloud accounts. The effect is a significant inflation of reported open rates for Apple Mail users, as every email delivered appears as an open, regardless of actual user interaction. The feature stops senders from using invisible pixels to gather information.
Google or 
Yahoo) filter incoming mail. Spam filters and inbox placement algorithms rely on a multitude of signals beyond just image opens, including real user behavior, authentication (SPF, DKIM, DMARC), spam complaints, and direct interactions. Therefore, while marketing teams need to adjust their reporting, email deliverability itself should not be directly impacted by the change in open rate data, as confirmed by providers like 
Hubspot.
