How does Apple's MPP affect email marketing?

In short: Apple’s Mail Privacy Protection (MPP) hides whether, when, and where a recipient opened an email, which makes open rates unreliable and inflated for Apple Mail users. It doesn’t hurt deliverability—your mail still lands—but it does mean you should measure success by clicks, conversions, and other intentional actions rather than opens.

Internet privacy is becoming increasingly important to all internet users. With most businesses migrating online and everyone’s reliance on the internet for day-to-day activities, having a highly protected internet connection is critical. In an attempt to maximize their profits, companies track your online behavior and offer ads relevant to your internet searches.

To address this, Apple’s privacy team has worked to keep their customers’ data safe from third parties. In September 2021, they introduced Mail Privacy Protection (MPP) as part of iOS 15, a feature that shields users’ IP addresses from trackers and hides email opens. (It’s a built-in Apple Mail setting, not a law or an “act.”)

Apple's MPP – An infographic.

What is MPP?

Mail Privacy Protection lets Apple Mail users control what senders can learn about them. When enabled, it prevents email senders from knowing whether their emails were opened—which affects one of the most-watched email metrics: open rate. Open rates have long been used to gauge campaign performance, so anything that obscures them changes how marketers measure success.

MPP is opt-in and available to anyone using the Apple Mail app on an updated Apple device (iPhone, iPad, or Mac). It applies only to people who use Apple Mail and turn the feature on—it does not affect Gmail, Outlook, or other apps, even on an Apple device. Industry estimates have often put MPP-affected opens at a large share of an Apple-heavy list, so for many senders the impact is substantial.

How does MPP work?

The feature makes use of the invisible tracking pixels that senders embed to detect opens. It prevents third-party tracking by masking IP addresses and hiding when users open their emails, making it impossible to link an open to other online activity or to a specific location.

Apple does not enable MPP by default, so users choose whether to use it. To turn it on, a user opens the Settings app, goes to Mail → Privacy Protection, and enables Protect Mail activity. You can read Apple’s own overview of Mail Privacy Protection for the current steps and behavior.

So what happens when an Apple user enables “Protect Mail activity”?

When the user’s Mail app receives a new-mail notification, Apple triggers a download of the email.
Apple routes the email through a proxy server, which pre-loads the content of the email, including any tracking pixels.
It downloads the images in the message (immediately or later) and caches a copy on Apple’s servers. Because a proxy pre-loads the message, the recipient’s actual IP address is hidden.
Fetching those images issues a request to the email service provider (ESP), prompting the ESP to record an “open”—whether or not the person ever looked at the email.
If the user does open the email, the images are served from Apple’s cache rather than from the sender’s ESP.

Consequently, MPP makes it impossible to reliably determine when an email was opened, by whom, and where, via the Apple Mail app.

How does MPP impact email marketing?

Because MPP disguises the device’s IP address and pre-loads content, it has a significant impact on open rate. Open rates are no longer a reliable indicator of success for Apple Mail users, and location-based tactics can’t depend on a verified location. The most prominent impacts are:

Open rates are inflated and unreliable – Because Apple pre-loads content, ESPs record “opens” that may never have happened, often pushing Apple-Mail open rates to near 100%. Reports can show a sharp, artificial rise in opens, undermining the metric’s legitimacy. Industry analyses in 2025 estimated that a large share of reported opens in some segments were machine-generated.
Open-based features have grown less reliable – Many email tools were built around opens. Affected features include:

List segmentation – Segmenting by “most engaged opener” no longer works reliably; segment on specific link clicks instead.
Email testing – A/B tests decided on open rate are now skewed; judge subject-line and content tests on clicks and downstream actions.
Follow-ups to non-openers – “Resend to unopened” misfires, because MPP registers an open for Apple Mail users regardless; base resends on click activity instead.
Open-triggered automation – Workflows keyed to opens fire unpredictably; trigger them from clicks or other intentional actions.

Timestamps and location can’t be verified – Because Apple’s proxies pre-load messages, you can’t reliably tell where or when an Apple Mail user opened an email, so open-based location and send-time targeting are no longer dependable.
Open-based personalization breaks down – Tactics that single out “most frequent openers” don’t hold up; personalize from clicks, purchases, and profile data instead.

Worth knowing: the change didn’t stop with opens. Since iOS 17 and expanding with iOS 18 (late 2024), Apple’s Link Tracking Protection strips certain tracking parameters from links opened in Apple Mail and Safari. Standard aggregate UTM parameters (like utm_source and utm_campaign) generally survive, but personal cross-site identifiers (such as fbclid and gclid) are removed—so click attribution through Apple can be affected too. Using your ESP’s redirect/click-tracking domain (as Zoho Campaigns does) preserves click measurement, since the parameters are handled at redirect. iOS 18 also added AI-generated inbox previews (which can override your preheader) and Gmail-style inbox categories, both worth designing around.

How can email marketers combat the effects of MPP now?

All is not lost—Zoho Campaigns can help you neutralize MPP’s effects. A few tips to counter it:

Rely on click rates to measure success. Include clear CTAs in every email to drive clicks and build a click-rate benchmark you can evaluate against.
Send follow-ups based on click activity. Zoho Campaigns lets you send follow-ups off clicks instead of opens, so you re-engage on a signal MPP can’t fake.
Tweak click-based automation. Build onboarding and nurture series on clicks, and re-engage inactive contacts with CTA-led workflows using Zoho Campaigns’ activity-based conditional workflows.
Explore other engagement metrics. Look at conversions, replies, website visits, and unsubscribe trends to build a fuller picture of performance.
Clean your lists regularly. Because opens can no longer flag inactive contacts, disciplined list pruning matters more than ever for deliverability.
A/B test on clicks. Test as often as you can using clicks (not opens) and act on the winners—see our guide on using subject lines to drive engagement.
Use a seed list. Seed lists let you evaluate rendering and inbox placement in real time, independent of open tracking.
Audit your open-rate dependencies. Identify, evaluate, and update any current activities that lean on open rate.
Report on clicks. Put click rate (and conversions) front and center in the reports and dashboards you review regularly.

A practical note on opens: rather than discarding them entirely, many teams now split openers into “high-confidence” (opened and clicked) and “low-confidence” (opened only, likely MPP) and lean on the first group. If your list skews toward Apple Mail, consider excluding MPP opens in your reporting so your baselines stay meaningful.