Open Rate
Email MarketingAlso: Email Open Rate · Message Open Rate
Quick definition
Open rate is the percentage of delivered emails that are opened, calculated as unique opens divided by emails delivered, expressed as a percentage. Since Apple Mail Privacy Protection (MPP) launched in 2021, open rate figures are significantly inflated for many senders and should be treated with caution.
If a large portion of your list uses Apple Mail or iOS Mail, this figure is inflated by machine-opens. Use click rate and revenue per email as your primary health indicators.
How it varies across Australia
Open rates across Australian email programmes have shifted upward since Apple Mail Privacy Protection arrived, but the lift is artificial. Programmes that relied on open rate as a primary engagement signal now show inflated figures that mask real list health. The better signals are click rate, click-to-open rate and revenue per email sent.
See email engagement benchmarks across Australian industries →What it actually means
Open rate measures the share of people who received your email and opened it. It sounds straightforward. A tracking pixel loads when the email is opened and the platform records it as an open. The problem is that Apple Mail Privacy Protection (MPP) pre-loads those pixels on Apple's servers before the subscriber ever looks at the email, recording a phantom open regardless of whether anyone read a word.
For Australian senders, MPP affects a large proportion of the subscriber base because Apple Mail and iOS Mail have high adoption locally. The result is that reported open rates for many programmes are now materially overstated. An open rate that looks healthy may be hiding a disengaged list.
Open rate still has value as a relative metric. If your open rate drops sharply, something changed: deliverability, subject line quality, send frequency or list health. The absolute number is less meaningful than it used to be. The trend still signals something real.
The better engagement indicators now are click rate (actual clicks divided by delivered), click-to-open rate (clicks divided by opens, which filters for intent among apparent openers), and revenue per email sent for ecommerce programmes.
Open rate used to be a rough proxy for attention. Now it's a rough proxy for how many of your subscribers use Apple Mail.
How to calculate it
Open Rate = Unique opens ÷ Emails delivered × 100
Worked example. You send to 10,000 subscribers. 200 emails bounce and are not delivered. Of the 9,800 delivered, your platform records 2,940 unique opens. Open Rate = 2,940 ÷ 9,800 × 100 = 30%. Note: if a significant share of your list uses Apple Mail, a portion of those recorded opens are machine-generated and not genuine.
The Australian context
Australia has high adoption of Apple devices and Apple Mail, which makes Apple Mail Privacy Protection a particularly significant distortion factor for Australian email senders. Many local email marketers noticed their reported open rates climb sharply from late 2021 without any real change in engagement.
This matters practically for list management. Suppression logic that relied on 'no opens in 90 days' as the trigger for a re-engagement or sunset flow now captures fewer genuinely disengaged subscribers, because machine-opens keep apparent engagement artificially alive. Any Australian sender using open-based suppression should audit whether their logic still removes truly inactive contacts.
Where people get this wrong
Related terms
Common questions
Why did my open rate jump without me changing anything?
Almost certainly Apple Mail Privacy Protection. When subscribers use Apple Mail or iOS Mail, Apple pre-loads your tracking pixel on their servers before the email is read, recording an open regardless of whether anyone looked at it. The jump in your data coincides with when MPP rolled out or when your list composition shifted toward Apple users.
Is open rate still worth tracking at all?
Yes, as a relative signal. If your open rate drops sharply, something changed: deliverability, subject line quality, send frequency or list health. The trend still flags problems worth investigating. As an absolute number or a primary health KPI, it's no longer trustworthy.
What should I use instead of open rate as my primary email metric?
Click rate for engagement, click-to-open rate for intent quality among apparent openers, and revenue per email sent for any programme with a commerce component. These metrics require actual human action and are not distorted by machine-opens.
How do I fix my re-engagement flows if I can't trust open rate?
Replace open-based triggers with click-based or purchase-based triggers. A subscriber who hasn't clicked or purchased in 90 to 120 days is a better definition of inactive than one who hasn't opened. Update your suppression logic to use click activity as the primary signal.
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About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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