Do open rates still matter post-MPP?

Your dashboard says opens are up. But you know something's off. Ever since Apple Mail's Mail Privacy Protection (MPP) launched in 2021, a chunk of those opens has been fake. Apple's proxy servers pre-fetch email content the moment it hits a subscriber's device, whether they actually read your email or not. That pre-fetch fires your tracking pixel, and your ESP logs it as an open.

So no, open rates don't mean what they used to. But that doesn't mean you throw them out entirely.

The problem is really about segment mix

MPP only affects Apple Mail users. Subscribers reading on Gmail, Outlook, or other clients aren't affected by this (at least not yet). So the more Apple Mail users you have in your list, the more inflated your overall open rate looks. If you're sending to a tech-savvy, mobile-heavy audience, that can be a lot of people. If your list skews toward enterprise Outlook users, it matters less.

Most ESPs now allow you to see which email client your subscribers use. It's worth checking. If 40 or 50 percent of your list is on Apple Mail, you can't trust your aggregate open rate at all. If it's closer to 10 or 15 percent, opens from your non-Apple segments are still reasonably accurate.

What to track instead (or alongside)

Here's where click data becomes your new best friend. Clicks require a human to actually choose to interact. They can't be faked by a proxy server. Same goes for replies, purchases attributed to email, and form completions. These are the metrics that reflect real behavior.

• Click-to-open rate (CTOR): Compare clicks against opens. A high open rate with very low clicks is a red flag that your opens are inflated.
• Click rate overall: What percentage of your total sends get a click? This is a more honest number.
• Reply rate: Even small reply volumes are a strong engagement signal for deliverability.
• Conversion tracking: Purchases, signups, downloads attributed to email. This is the real number your business cares about anyway.

Should you stop using opens for anything?

Not completely. Opens still work reasonably well for directional trends over time within the same audience. If your opens drop sharply month over month, something changed, even if the absolute number is inflated. They're also fine for identifying engaged vs. unengaged segments among your non-Apple subscribers.

Where opens fail you is in comparisons across campaigns, comparisons across audiences with different device mixes, and especially in re-engagement decisions. If you're about to sunset a segment of "unengaged" subscribers based purely on open data, that logic breaks down fast. Some of those "non-openers" might be clicking every week. (Check clicks before you suppress anyone.)

If you're not sure how bad the MPP impact is on your specific list, our SOS hotline is free and we'll help you work through what your numbers actually mean.