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Posted At: Mar 27, 2026 - 1,496 Views

Email Open Rates: Why They're Becoming Less Reliable and Which Metrics to Track in 2026

Your last campaign shows a 45% open rate. Pretty good — except that some of those “opens” probably never corresponded to anyone actually reading the email. Since Apple Mail Privacy Protection (MPP), the open rate has become an increasingly difficult metric to interpret.

Klaviyo, Litmus and Brevo now say so explicitly: opens are still useful as a trend signal, but they're no longer enough to measure an audience's real engagement.

What Is Apple MPP and Why Does It Skew Opens?

With Apple Mail Privacy Protection, Apple preloads email content on its servers. The result: an email can show up as “opened” even if the subscriber never actually looked at it.

That's what makes the open rate far less reliable than it used to be. Some of your opens now come from machine behavior, not from a real human action.

And the effect isn't marginal: according to Litmus, Apple accounted for 45.51% of observed opens in February 2026. Litmus also states that opens coming from Apple Mail Privacy Protection should not be considered reliable opens.

Brevo has adapted its reports too: since February 6, 2025, Apple MPP opens have been included in the open rate, and since July 8, 2025, bot activity can also inflate open and click rates if you don't filter out these events.

What Klaviyo Officially Says About Open Rates

Klaviyo is very clear: open rates have become largely unreliable since iOS 15. The platform explains that Apple “opens” emails for users who have enabled MPP, even if those users never actually read them.

Klaviyo nevertheless notes that the open rate can still be useful as a directional metric — for example, to observe an overall trend — but that it should no longer be treated as the absolute truth or as the basis for overly rigid segmentation.

In its 2026 benchmarks, Klaviyo draws on more than 183,000 customers and puts more emphasis on metrics that are genuinely tied to business performance. In particular, the platform points out that automated flows generate nearly 41% of total email revenue from just 5.3% of sends, with revenue per recipient almost 18 times higher than that of regular campaigns.

What Litmus Recommends Measuring Instead

Litmus recommends treating the open rate as a mere trend metric. In its 2026 guide, the platform explains that it is “effectively broken” because of Apple MPP and should no longer be used as the absolute truth or as the basis for hard segmentation.

Instead, Litmus recommends steering by indicators that are closer to a real human action or a concrete business impact:

  • Click-through rate (CTR) — a more reliable indicator of human interaction than opens
  • Click-to-open rate (CTOR) — useful for judging content relevance, with caution
  • Read rate / reading time — to distinguish a quick display from genuine content consumption
  • Revenue per recipient — the most direct business metric for an online merchant
  • Unsubscribe rate — a useful signal of fatigue or poor targeting
  • Spam complaint rate — a critical indicator for sender reputation

What This Means in Practice for a Shopify or PrestaShop Merchant

If you still use the open rate to segment your contacts into “active” and “inactive”, you risk making bad decisions. Some subscribers classified as engaged may not really be engaged, while other, more important signals — clicks, conversions, complaints, unsubscribes — get pushed into the background.

In practice, it makes more sense to trigger a re-engagement flow based on inactivity in clicks or purchases rather than on opens alone. For example: no clicks in 60 or 90 days, no purchase within a defined period, or a steady decline in the revenue generated per segment.

This also makes the quality of your list even more important: a clean list, free of invalid, disposable or risky addresses, produces much more reliable click and conversion metrics — and protects your sender reputation regardless of artificially inflated opens.

GTMailHygiene for Shopify helps you keep a cleaner list by identifying the invalid, disposable or risky addresses that distort your engagement signals. MailHygiene PRO for PrestaShop does the same job on the PrestaShop side.

Which Metrics Should You Prioritize in 2026?

  1. CTR to measure real interaction
  2. Revenue per recipient to connect email to sales
  3. Unsubscribe rate to detect fatigue or poor targeting
  4. Spam complaint rate to protect deliverability
  5. Actual list quality to keep invalid addresses from degrading every other metric

The Bottom Line

The open rate hasn't disappeared entirely — but it can no longer be used on its own to measure engagement. In 2026, the metrics that really count are the ones based on a real human action or a concrete business impact: clicks, revenue, complaints, unsubscribes and list quality.

If you want cleaner metrics and more reliable marketing decisions, start by cleaning up your contact list before drawing conclusions from your campaign reports.

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