Apple killed open rate. Most cold email agencies still report on it.

If your outbound dashboard still leads with open rate, your team is optimising for a metric that does not exist anymore.

This is not hyperbole. In September 2021, Apple launched Mail Privacy Protection in iOS 15. Every time a Mail.app user opens any email, their device pre-loads all tracking pixels in the background, regardless of whether they opened the email. The provider sending the email sees an "open" event for every Apple Mail user, whether or not the email was actually opened. Apple documents this as a privacy feature that hides the recipient's IP address and prevents senders from knowing when (or whether) an email was opened.

Within 6 months of launch, the share of Apple Mail users with MPP enabled crossed 90%. Today it is the default, and adoption keeps climbing as iOS users upgrade.

What this means for cold email

Your reported open rate is now a mix of three things:

• Real opens: the email was read by a human. Useful signal.
• Apple MPP pre-loads: the email landed on an Apple Mail device. Counted as opened, but the user may not have read it (or may not have even seen the subject line in their inbox).
• Bot opens: corporate email security scanners and inbox preview engines that automatically load pixels before a human ever sees the email.

For typical B2B cold campaigns, around 50-65% of reported opens are now non-human. The exact share depends on how Apple-heavy your target audience is (US-based founders skew higher, European IT departments lower).

A campaign reporting 70% opens probably has 25-30% real opens. The other 40+ percentage points are noise.

What does still work as a metric

Three categories of cold email metrics are reliable in 2026:

1. Bounces

Hard bounces and soft bounces. These come back from the receiving mail server and are entirely server-to-server. No pixel involved. Bounce rate above 5% is a deliverability emergency. Aim for below 3%. Gmail Postmaster Tools exposes domain-level reputation and spam-rate signals for the same reason: server-side feedback is the only deliverability data you can trust.

2. Reply rate

A reply is a human action that travels back to your sender inbox. Cannot be faked by pre-loading. Use this as your top-of-funnel signal.

3. Positive reply rate (PRR)

Of all replies, the share that signal interest. The rest are unsubscribes, out-of-office, wrong-person, or angry "remove me". PRR catches list quality issues that reply rate alone hides. closed:in benchmark: 33% PRR is healthy.

The metric we report instead: opportunity-to-reply ratio (OTR)

The single most useful cold email metric is OTR: qualified opportunities divided by total replies. It catches the failure mode that reply rate alone hides.

A campaign with a 30% reply rate sounds amazing. Until you find out 90% of those replies are "not interested" or "remove me". Your SDRs spend their day reading no's. Pipeline does not move.

A campaign with a 5% reply rate and 50% OTR generates more revenue than the 30% reply / 5% OTR campaign. Same input cost, very different output.

Real numbers from a closed:in client (Verzendbazen):

• 9,500 emails sent
• 13.9% reply rate
• 78 qualified opportunities from ~1,300 replies
• 6% OTR
• €78K pipeline

For reference, agencies that obsess over reply rate alone often report 0.5-2% OTR. They are running fast on the wrong metric.

What to do tomorrow

1. Remove open rate from any dashboard your sales team looks at daily. It is noise.
2. Add OTR as a tracked metric. Pipe positive replies into your CRM and count qualified opps weekly.
3. If you have to report on open-related stats, use unique opens not total opens, and put a footnote explaining MPP inflation.
4. For deliverability monitoring, watch bounce rate and reply rate as your two leading indicators. If bounces creep up, your list hygiene is slipping. If replies drop, your copy or list is degrading.

The teams still leading dashboards with open rate are not lying intentionally. They just have not noticed the metric stopped working. If you are paying an agency that reports on it, ask them about MPP and watch the response.