How does Apple Mail Privacy impact IP warmup strategy and open rate tracking?

Key findings

• Inflated open rates: MPP pre-fetches all images (including tracking pixels) when an email arrives in the inbox, regardless of whether the user actually opens it. This inflates reported open rates for Apple Mail users, making them an unreliable indicator of true engagement.
• IP address masking: MPP hides the recipient's IP address, routing traffic through Apple's proxy servers. This obscures geographical location data and makes it harder to identify individual user behavior based on IP.
• Warmup methodology remains: The core principles of IP warming (gradually increasing volume, sending to engaged users) remain the same. MPP doesn't alter how ISPs perceive sender reputation based on sending volume and engagement patterns, but rather how opens are reported.
• Shift in metric focus: Marketers should de-emphasize the individual open rate as a primary success metric and focus more on other engagement signals like clicks, conversions, and subscriber list health to assess deliverability and campaign performance. More on this here: Klaviyo's insights on leveraging open rates
• Impact on deliverability signals: While opens are less reliable, other key factors such as spam complaints, bounces, and click-through rates still provide crucial insights into deliverability during IP warmup. Monitoring these remains critical for maintaining sender reputation.

Key considerations

• Adjusting open rate interpretation: Do not abandon open rate tracking entirely. Instead, use it to observe trends over time rather than exact per-send performance, particularly for Apple users. Inflated opens can still show a baseline of deliverability.
• Focus on other engagement metrics: During warmup, prioritize clicks, conversions, and replies. These actions provide a more accurate picture of recipient engagement post-MPP. Monitoring list health and unsubscribe rates is also vital.
• Segmentation: If possible, segment your audience by email client to isolate Apple Mail users and analyze their engagement separately. This can help prevent the inflated open rates from skewing overall campaign insights.
• Monitoring spam folder placement: MPP's auto-open does not fire if the email lands in the spam folder. Therefore, a sudden drop in reported opens (even inflated ones) for Apple users could still indicate a deliverability issue. This aligns with observations about how Gmail's image proxy works similarly.
• Leverage postmaster tools: Utilize Google Postmaster Tools and other ISP feedback loops to get direct deliverability insights not affected by MPP's open rate inflation, such as spam complaint rates and reputation scores. You can read more about MPP's impact on email marketing here.

Key opinions

• Open rate inflation is real: Marketers widely acknowledge that open rates are significantly inflated by MPP, especially for Apple users, making direct comparisons to pre-MPP data challenging.
• Opens still matter for trends: Despite the inflation, many marketers believe open rates can still be valuable for identifying overall trends, spotting sudden dips that might indicate deliverability issues, and serving as a 'canary in the coal mine'.
• Shift to clicks and conversions: There's a strong consensus to prioritize click-through rates (CTR) and conversion metrics as more reliable indicators of engagement and campaign success in a post-MPP world.
• Warmup process is unchanged: The core methodology for IP warming itself remains the same, focusing on gradual volume increases and positive engagement signals, even if open rates are skewed.
• False expert advice: Some marketers express frustration with advice to completely abandon open rate tracking, arguing that it still provides some value for identifying general deliverability health, particularly for non-Apple users.

Key considerations

• Segment Apple users: Where possible, segmenting your audience based on email client (especially Apple Mail vs. others) can help provide clearer insights into actual engagement versus MPP-inflated opens.
• Redefine success metrics: Adjust your campaign goals and reporting to emphasize metrics that are less affected by MPP, such as clicks, conversions, unsubscribes, and spam complaints.
• Beyond the open: During warmup, focus on sending highly engaging content that encourages clicks and other direct interactions, which are more reliably tracked and provide stronger signals to ISPs.
• Monitor deliverability holistically: Rely on a broader set of indicators, including bounce rates, spam complaints, and overall list hygiene, to gauge the health of your IP warmup process.
• Adapt reporting: Educate stakeholders on the changes brought by MPP and adjust reporting dashboards to reflect the new reality of open rate data. You can find more strategies for open rates post-iOS 15 here: Klaviyo's guide to open rate metrics

Key opinions

• IP warmup methodology is largely unaffected: Experts confirm that the core process of IP warming remains the same, focusing on gradually increasing volume and building sender reputation through consistent, positive sending behavior.
• Opens are a 'false metric' for precision: Measuring opens along the warmup path will yield inflated data due to MPP, making it difficult to use them for precise, individual engagement assessment or to definitively pinpoint spam folder placement solely via open rates.
• Opens still useful for trends and outliers: Despite inflation, experts agree that open rate trends can still be valuable for identifying overall deliverability health and spotting significant deviations or issues over time.
• Beware of image load assumptions: Professionals advise against equating every image load request from Apple's proxy to an actual user open, reinforcing the need for a more nuanced understanding of engagement.
• Spam folder interaction with MPP: There's an important distinction that MPP's auto-open pixel may not fire if an email lands in the spam folder, making a drop in opens a potential indicator of deliverability problems.

Key considerations

• Holistic deliverability monitoring: During IP warmup, rely on a comprehensive set of metrics including clicks, unsubscribes, complaints, and direct engagement signals, alongside contextual open rate trends. More information on Internet Service Providers tracking engagement.
• Educate on open rate limitations: It is crucial to communicate to marketing teams and stakeholders that open rates for Apple Mail users are inflated and should not be used for precise audience engagement measurement.
• Optimize for clicks: Focus on driving clicks and other post-open actions in your email content, as these provide stronger and more accurate engagement signals.
• Monitor spam folder behavior: Pay close attention to overall deliverability health indicators. If emails start landing in spam, the absence of MPP-inflated opens can still be a diagnostic clue, as the auto-pixel generally doesn't fire for spam. This is important for managing email deliverability for large sends.
• Utilize diverse tools: Combine insights from your ESP, ISP postmaster tools, and other deliverability monitoring platforms to gain a comprehensive view of your email performance during warmup.

Key findings

• MPP functionality: Documentation explicitly states that MPP works by preventing senders from knowing the exact open time and masks the recipient's IP address. This is achieved by routing all email image loads through Apple's proxy servers.
• Tracking pixel preloading: When MPP is enabled, Apple's proxy servers download tracking pixels when the Mail application is opened and the mailbox is updated, not necessarily when the user views the email. This leads to inflated or inaccurate open rates. Learn more about email tracking pixels and deliverability.
• IP address anonymization: Apple's proxy network randomly assigns an IP address to hide the user's actual location, impacting location-based segmentation and analysis.
• Impact on metrics: Documentation across platforms consistently highlights that open rates will be inflated, resulting in skewed metrics. This necessitates a re-evaluation of how marketers interpret campaign performance.
• Deliverability is distinct from open rates: While open rates are affected, the underlying deliverability to the inbox is not directly blocked by MPP, but rather the visibility into engagement. The email's journey to the inbox (and not spam) is still critical.

Key considerations

• Adapt email analytics: Documentation advises adjusting analytics to focus on metrics less impacted by MPP, such as clicks, conversions, and direct responses, to gain meaningful insights.
• Understanding IP warmup context: IP warmup still relies on building a positive sender reputation with ISPs through consistent sending. MPP doesn't change this, but means open rates during warmup should be viewed as a baseline rather than true engagement. For specific strategies, refer to IP and domain warm-up strategies.
• Monitor deliverability: Despite MPP, it's crucial to monitor deliverability through other means like spam complaints, bounce rates, and feedback loops to ensure emails reach the inbox. More details on iOS 15 and deliverability impacts.
• Server-side vs. client-side: It's important to understand the distinction between server-side deliverability (whether the email reaches the recipient's mail server) and client-side engagement (whether the user actually opens it in the mail client). MPP affects the latter's measurement.
• Data for segmentation: While IP addresses are masked, other demographic or behavioral data (e.g., website activity) can still be used for segmentation and personalization to maintain relevant email campaigns. You can check the documentation on working with Apple Mail Privacy Protection here.