# Open Rates + Apple MPP: What AcelleMail's Numbers Actually Mean

> Apple Mail Privacy Protection inflates 30-45% of your "opens" by pre-fetching pixels. This guide shows how to spot MPP inflation in AcelleMail (open-log IPs), what to measure instead, and how to adjust your A/B tests + reporting.

- Canonical URL: https://acellesend.com/kb/articles/understanding-email-open-rates-in-the-age-of-apple-mpp
- Author: Ryan Walsh, Audience & Analytics Editor
- Category: Analytics & Reporting — Open rates, click maps, campaign performance, device reports, exports
- Content type: guide · Difficulty: intermediate
- Tags: Open Rates, Analytics, Acellemail
- Published: 2026-01-31 · Last updated: 2026-08-15
- Reading time: 7 min
- Publisher: AcelleMail Knowledge Base, https://acellesend.com/kb

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## What this is for

Your AcelleMail open-rate number is wrong. Not because AcelleMail is broken — because **Apple Mail Privacy Protection (MPP)** pre-fetches the tracking pixel that every ESP uses to record opens. Every email delivered to an MPP-enabled inbox registers as "opened" the moment Apple's proxy fetches it, regardless of whether a human ever read it.

This article shows how to spot MPP inflation in AcelleMail's reports, what an "open" actually means now, and which metrics to optimise instead.

## What MPP does (and why it kills open tracking)

Since iOS 15 (September 2021), Apple's mail apps automatically:

1. **Pre-fetch every image** in an email — including the invisible 1×1 tracking pixel that ESPs use to count opens
2. **Route the fetch through Apple proxies** — so the IP / location AcelleMail records is Apple's data center, not the user's device
3. **Pre-fetch on delivery**, not on user-open — so the open registers BEFORE the user has even seen the email (or ever will)

**Result:** every campaign sent to an Apple Mail user with MPP enabled records as opened. Open rates look fantastic. They aren't.

## How widespread

By industry rough numbers:

| Segment | Share of all email opens (approx.) | MPP-affected |
|---|---|---|
| Apple Mail (iOS + macOS) | 35-50% | 80-90% of these |
| Gmail | 25-35% | Not MPP-inflated (own tracking) |
| Outlook desktop + web | 10-20% | Not MPP-inflated |
| Yahoo / AOL / Others | 5-15% | Not MPP-inflated |

**The math:** if Apple Mail is 45% of your audience and 85% of those have MPP, then **~38% of your "opens" are MPP-inflated.** Your real engagement is significantly lower than the dashboard suggests.

The exact ratio depends on your audience:

- **Consumer / lifestyle / mobile-first lists** — skew heavily Apple, expect 40%+ MPP inflation
- **B2B / enterprise lists** — skew Outlook, expect <15% MPP inflation
- **Mixed audience** — split roughly to the industry average above

## How to spot MPP inflation in AcelleMail

There's no direct "MPP filter" toggle in the refactor UI, but the **open log** tells you exactly what's happening: every open is logged with the IP address that fetched the pixel. Apple proxies have telltale IP ranges.

Open any sent campaign → **Sending logs** tab. (Or directly: `/campaigns/{uid}/open-log`.)

![Open log view (Sending logs tab) for "Holiday Edition 35" showing per-recipient open records with columns Recipient · IP Address · Location · Date. Multiple rows show subscribers (benjamin@valenzuela.org, carrillogeoffrey@roberts-gould.com, etc.) opened from IPs like 157.50.100.20, 99.50.100.10, 100.10.50.5, with Location dashes (—) and dates "1 hour ago" / "2 hours ago".](https://acellesend.com/plugins/acelle/landing/images/help/kb/analytics/08-open-log.png)

What to look for:

- **Location column showing "—"** (no city) — strong signal of Apple proxy
- **Date clustering** — many opens recorded within 1 minute of each other, hours apart from when the user is plausibly awake — pre-fetch behaviour, not human behaviour
- **Many opens from a small set of IP ranges** — Apple uses a finite pool of proxy IPs; you'll see the same IPs across hundreds of subscribers if MPP is heavy

If 30-50% of opens have the *"—"* location pattern + cluster suspiciously, **roughly that share is MPP-inflated.** Subtract that mentally from your headline open rate to get a more realistic estimate.

## What the Overview tab actually tells you

When you read the campaign report, the headline number is no longer trustworthy on its own.

![Campaign Overview tab showing "Holiday Edition 35" with banner "Solid performance — Your open rate of 24% is on track. Consider A/B testing subject lines to push it higher" and stat cards RECIPIENTS 14,794 / DELIVERED 3,838 / OPENED 931 (24.26%) / CLICKED 146 (3.80%). Rate summary panel showing Opened 24.26%, Did not open 75.74%, Clicked 3.80%](https://acellesend.com/plugins/acelle/landing/images/help/kb/analytics/01-campaign-overview.png)

(Screenshot from [Read the Campaign Report](https://acellesend.com/kb/articles/understanding-email-analytics-and-key-metrics).)

For "Holiday Edition 35":

- **Dashboard says: 24.26% open rate** (931 of 3,838 delivered)
- **MPP-adjusted (if 40% of audience is Apple): ~14-18% real open rate**
- **CTR (click rate) = 3.80%** — this number is NOT MPP-inflated. Clicks require real human action.

The CTR is the reliable number. If you only look at one metric for engagement, **click rate** is the one.

## What to measure instead

The MPP era is forcing email marketers to shift to metrics that survive the inflation:

| Metric | Why it survives MPP |
|---|---|
| **Click rate (CTR)** | Clicks require a human tapping a link — pre-fetch doesn't trigger clicks |
| **Click-to-open rate (CTOR)** | Less affected because clicks are real; the *denominator* (opens) is inflated, so CTOR appears lower than it should — but the metric is still comparable campaign-to-campaign |
| **Revenue per recipient** | The only metric that matters commercially. Untouched by MPP. |
| **Unsubscribe rate** | Real signal of fatigue / mismatch. Untouched by MPP. |
| **Reply rate** | For 1-to-1 / sales emails — direct human engagement |
| **Conversion rate** (purchase, signup, etc.) | The downstream business goal — what you actually optimise for |

**Stop optimising for opens.** Re-orient your A/B tests, your subject line decisions, and your dashboards around **clicks + conversions**. Open rate becomes a quick sanity check — *"did anyone even see this?"* — rather than the primary KPI.

## How to adjust your A/B testing

If you're running A/B tests on subject lines (see [A/B Test Campaigns](https://acellesend.com/kb/articles/ab-testing-email-subject-lines-for-better-open-rates)), the **Winner Rules** tab lets you pick the win condition:

| Choice | Recommended? | Why |
|---|---|---|
| **Highest open rate** | ❌ Not anymore | MPP inflates both variants equally, but adds noise. Differences <5% are basically random. |
| **Highest click rate** | ✅ Yes | Real signal. Use this for subject + content tests. |
| **Manual selection** | ✅ When testing revenue or conversion | Pull data from your backend; pick the winner by what actually drove dollars. |

For most A/B tests in the MPP era, **switch the winner metric from open rate to click rate** by default.

## How to read open rate when you can't avoid it

Despite the inflation, you still have to report open rate to executives, comparison-shop campaigns over time, and benchmark against industry numbers. Three honest approaches:

1. **Report it as "raw open rate" + caveat.** Add a footnote: *"Open rate inflated ~30% by Apple MPP pre-fetch. CTR is the more reliable engagement metric."*
2. **Report the trend, not the absolute number.** If your open rate went from 24% to 32% campaign-over-campaign, that's still a real lift (assuming MPP share stayed constant). Trend > absolute.
3. **Build an "engaged opener" segment** — subscribers who have **clicked** in the last 30 days. Their "open rate" in your analysis is a real human metric.

## What to do, ranked by impact

| Priority | Action |
|---|---|
| 1 | Switch primary KPI from open rate to **click rate** in dashboards |
| 2 | Re-run A/B tests on subject lines using **click rate** as winner condition |
| 3 | Build engagement-based segments off **clicks**, not opens |
| 4 | Don't change re-engagement thresholds yet — using opens > 90 days for sunset still works because Apple subscribers' opens are *consistently* inflated; the relative comparison holds within a single subscriber's history |
| 5 | Update internal reporting templates to caveat open rate |

## What NOT to do

- **Don't compare your post-2021 open rates to pre-2021 numbers** — they're not the same metric. You'll look like a hero or a failure for spurious reasons.
- **Don't try to "filter out" MPP opens in AcelleMail.** There's no reliable way to do this client-side; Apple intentionally mixes in real opens with prefetches.
- **Don't switch ESPs hoping MPP will be solved.** Every ESP has the same problem. This is industry-wide.
- **Don't tell your team "open rate is dead."** It's still useful as a directional / trend signal — just stop using it as your primary KPI.

## Common questions

| Question | Answer |
|---|---|
| Will Google add similar MPP to Gmail? | Hasn't yet (as of 2026). Gmail uses its own tracking that's more accurate than the pixel. |
| If MPP inflates everyone equally, isn't it still useful for comparing campaigns? | Roughly yes — relative comparison within the same audience still works. But absolute numbers and benchmarks against industry are useless. |
| What about "Open Statistics → By Email Client" the docs mention? | That UI path doesn't exist in the AcelleMail refactor UI. Use the **Sending logs** tab + **Open log** sub-view to see per-open IP / Location, which surfaces Apple-proxy patterns. |
| Should I switch to text-only emails to bypass tracking? | Text-only emails have no images = no tracking pixel = AcelleMail can't measure opens at all. Useful for plain transactional, not for marketing. |

## Related articles

- [Read the Campaign Report: AcelleMail Analytics Tour](https://acellesend.com/kb/articles/understanding-email-analytics-and-key-metrics)
- [A/B Test Campaigns in AcelleMail](https://acellesend.com/kb/articles/ab-testing-email-subject-lines-for-better-open-rates)
- [Click Map Analysis: Optimise Your Email Layout](https://acellesend.com/kb/articles/click-map-analysis-optimize-your-email-layout)
- [Email ROI Calculation](https://acellesend.com/kb/articles/email-roi-calculation-measuring-campaign-profitability)

---

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