Email Marketing Metrics That Actually Matter (Open Rate Is a Lie)

Key Takeaways

• Open rate has been fundamentally unreliable since Apple introduced Mail Privacy Protection in 2021, which automatically pre loads the tracking pixel used to record an open for a huge share of subscribers, regardless of whether they actually opened the email at all.
• Click through rate remains one of the most honest, direct signals available, since a click requires a genuine, active decision from the subscriber that cannot be inflated by automated pre loading in the same way an open can.
• Click to open rate isolates the quality of your actual email content and call to action specifically, separate from how many people technically registered an open, making it a more precise diagnostic tool than either open rate or click through rate alone.
• Revenue per email connects your email activity directly to business outcomes, and is the metric most worth tracking if income, not just engagement, is the actual goal of your email program.
• List growth rate and unsubscribe rate together tell you whether your list is healthy and growing in a sustainable way, or quietly shrinking in engaged quality even while the raw subscriber count stays flat or grows.
• Deliverability, meaning the percentage of your emails actually reaching the inbox rather than the spam folder, is the metric that determines whether any of your other numbers mean anything at all, since a highly engaging email that never reaches the inbox produces no engagement whatsoever.
• Platforms like ConvertKit, Mailchimp, AWeber, and GetResponse all still display open rate prominently on their dashboards, and understanding why that number specifically should not be your primary success measure is essential to reading your own reports honestly.

Introduction

For years, open rate was the metric email marketers checked first, and often the only metric they checked at all. It felt intuitive, the percentage of people who actually opened your email, a direct, simple measure of how engaging your subject line and your relationship with your list actually were.

Then, in 2021, Apple quietly broke it. Mail Privacy Protection, a privacy feature introduced in iOS 15, automatically pre loads every email’s content, including the invisible tracking pixel used to record an open, the moment an email arrives in a Mail app inbox, regardless of whether the actual human being on the other end ever looks at it. For any subscriber using Apple Mail with this feature enabled, and a significant share of any list does, your open rate is being recorded as a near guaranteed open, whether or not a genuine, engaged reader ever saw the email at all.

Most email marketers know this has happened, in a vague, background sense. Far fewer have actually changed which numbers they treat as their primary success measure as a result. This guide covers the metrics that genuinely still reflect real subscriber engagement and real business results, why each one matters specifically, and how to build a reporting habit around the numbers that are actually still telling you the truth.

What You Will Learn

In this guide, you’ll learn:

• You will understand click through rate and click to open rate, and why both are more honest signals of genuine engagement.
• You will understand revenue per email and why it is the metric most directly tied to whether your email program is actually working as a business asset.
• You will understand list growth rate, unsubscribe rate, and deliverability, and how these three together reveal the underlying health of your list.
• You will understand how to build a reporting habit around these more reliable metrics instead of defaulting back to the open rate number every platform still displays first.

Why Open Rate Broke in 2021

Understanding exactly what happened is worth covering in detail, since the mechanism explains precisely why the number cannot be trusted the way it once could, rather than leaving it as a vague, general caveat.

Email open tracking has traditionally worked through a tiny, invisible tracking pixel, a one by one pixel image embedded in the email, that loads from the sending platform’s server the moment the email is opened and its images are displayed. That image load is what gets recorded as an open.

Apple’s Mail Privacy Protection feature, introduced in iOS 15 in September 2021, changed the underlying mechanics for any subscriber using Apple Mail with the feature enabled, which is the default setting many users never actively change. Instead of loading images only when a subscriber actually opens the email, Apple Mail proactively pre loads all remote content, including that tracking pixel, for every incoming email automatically, in the background, immediately upon arrival, regardless of whether the subscriber ever looks at it, opens the app, or even knows the email exists yet.

The practical effect is that any list with a meaningful share of Apple Mail subscribers, which is the case for the large majority of consumer facing email lists given how widely Apple’s devices are used, will show an inflated, artificially high open rate that does not distinguish between an email a subscriber genuinely read and an email that was never actually opened but had its tracking pixel triggered automatically anyway. For many lists, this means open rate is now measuring something closer to email delivery combined with Apple Mail market share, rather than genuine subscriber engagement in any meaningful sense.

The Metrics That Are Still Honest

Click Through Rate

Click through rate measures the percentage of delivered emails in which a subscriber clicked at least one link. Unlike an open, a click requires an active, deliberate decision from a genuine human being, one that cannot be triggered automatically by a mail client pre loading content in the background. This is precisely why click through rate has become the most trusted primary engagement metric in the post 2021 landscape, and it is the number most experienced email marketers now treat as their real headline metric.

A healthy click through rate varies by list size, niche, and email type, but the specific benchmark matters less than tracking your own trend over time, comparing your click through rate across different subject lines, different content formats, and different send times, since this internal comparison remains genuinely reliable even though open rate no longer is.

Click to Open Rate

Click to open rate divides your total clicks by your total opens, rather than by your total emails delivered, giving you a measure specifically of how compelling your email content and call to action were among the people who, at minimum, technically registered an open. This metric is genuinely useful as a content quality diagnostic specifically, isolating the performance of what happens inside the email from the performance of the subject line and send timing that drove the open itself.

It is worth being direct about a limitation here as well. Because the open number underlying this calculation is itself inflated by the Mail Privacy Protection issue covered above, click to open rate is a more precise diagnostic than open rate alone, but it inherits some of the same distortion, since the denominator includes those automatically triggered, non genuine opens. Treat it as a useful, relative, internal comparison tool rather than an absolute, standalone measure of quality.

Revenue Per Email

Revenue per email divides the total revenue attributed to a specific email send by the total number of emails delivered, connecting your email activity directly to actual business outcomes rather than stopping at an engagement proxy. This requires setting up conversion tracking, typically through UTM parameters on your email links combined with goal or conversion tracking in Google Analytics or your platform of choice, but the resulting number is the most directly meaningful metric available if your email program exists to drive real income, whether through affiliate links, covered in this site’s guide to how blogging makes money, or direct product and service sales.

Tracking this consistently over time also lets you directly compare the actual financial return of different types of email content, letting you make future content and promotional decisions based on genuine, historical revenue data specific to your own list, rather than general best practice guesses.

List Growth Rate

List growth rate accounts for new subscribers minus unsubscribes and hard bounces, measured against your total list size, giving you an honest picture of whether your list is genuinely growing in a healthy, sustained way. Email lists naturally decay over time, as subscribers change addresses, lose interest, or unsubscribe, which means a list that looks stable in raw subscriber count but has stopped attracting meaningful new signups is often quietly shrinking in genuine engagement even while the headline number stays flat.

Unsubscribe Rate

A small, steady unsubscribe rate after every send is completely normal and healthy, reflecting subscribers whose interests or circumstances have genuinely changed. A sudden spike in unsubscribes following a specific send, however, is a direct, honest signal that something about that particular email, its frequency, its relevance, or its tone, missed the mark significantly for a meaningful share of your list, and is worth investigating specifically rather than dismissed as normal variation.

Deliverability

Deliverability measures the percentage of your sent emails that actually reach a subscriber’s inbox, as opposed to being filtered into a spam folder or rejected entirely. This is, in a genuine sense, the foundation every other metric on this list depends on, since an email that never reaches the inbox has no chance of being opened, clicked, or converting into any revenue at all, regardless of how strong its content might otherwise have been.

Deliverability is influenced by your sender reputation, built up over time through consistent positive engagement signals, proper domain authentication through SPF, DKIM, and DMARC records, and consistent list hygiene, removing hard bounces and genuinely inactive subscribers rather than continuing to send to addresses that have stopped engaging entirely. Most major platforms, including Mailchimp, ConvertKit, AWeber, and GetResponse, provide some level of deliverability reporting, and it is worth checking this specifically rather than assuming a low click through rate is purely a content problem when it might actually be a delivery problem instead.

How to Read These Metrics Together

No single metric on this list tells the complete story on its own, and the real value comes from reading several of them together as a coherent picture rather than fixating on any one number in isolation.

A high click through rate combined with low revenue per email suggests your content is genuinely engaging and getting clicks, but something in the destination page or offer itself is not converting that interest into an actual outcome, a problem worth investigating using the honest, specific positioning principles covered in this site’s guide to comparison pages if the destination is a review or comparison page specifically.

A declining click through rate combined with a rising unsubscribe rate suggests a genuine content or relevance problem with your recent sends specifically, worth addressing directly rather than assuming it is simply normal list fatigue.

A shrinking list growth rate combined with stable or improving click through rate among your remaining subscribers suggests your existing audience genuinely likes what you are sending, but your top of funnel subscriber acquisition, covered in this site’s email marketing guide, has slowed and needs direct attention.

A sudden, unexplained drop across nearly every metric at once, including click through rate, is often a deliverability problem rather than a content problem, worth checking specifically before assuming your subject lines or content quality have suddenly and simultaneously declined.

Common Mistakes When Reading Email Metrics

Continuing to treat open rate as your primary success metric or headline number, despite it being systematically inflated by Apple’s Mail Privacy Protection feature since 2021, a change most platforms still do not make sufficiently clear on their default dashboard view.

Comparing your own open rate against generic, published industry benchmarks that predate or do not account for the post 2021 inflation, leading to a false sense of either success or failure based on a number that no longer means what it used to.

Never setting up revenue per email tracking at all, leaving your email program’s actual financial contribution to your business entirely invisible, and unable to be compared meaningfully against the time invested in producing it.

Assuming a low click through rate is always a content quality problem, without first checking deliverability specifically, when the underlying cause is sometimes that a significant share of the list is not receiving the email in their inbox at all.

Reacting to a single email’s unsubscribe spike as a crisis without first checking whether it correlates with a genuine content or relevance issue specific to that send, versus simply being normal, expected list churn.

Ignoring list growth rate entirely and only ever looking at engagement metrics among existing subscribers, missing a genuine top of funnel problem where new subscriber acquisition has quietly slowed or stopped.

Pro Tips for Better Email Metric Tracking

Set up UTM parameters and conversion tracking through your email platform and Google Analytics from the very beginning of your email program, rather than retrofitting revenue tracking later once you already have months of untracked sends behind you.

Build your own internal benchmark for click through rate specific to your own list and niche, tracked consistently over time, rather than relying on generic published industry averages that vary enormously by list size, niche, and audience relationship depth.

Segment your reporting by subscriber source where your platform allows it, since subscribers who joined through a specific, highly targeted lead magnet often engage very differently than subscribers who joined through a broader, more general opt in, and blending these together in a single average can obscure genuinely useful patterns.

Review your deliverability specifically at least quarterly, checking your platform’s dedicated deliverability reporting alongside your domain authentication settings, since a slow, gradual deliverability decline is one of the easiest problems to miss until it has already meaningfully damaged your results.

Treat any single send’s numbers as one data point rather than a verdict, and look instead at trends across several sends over time, since individual email performance naturally varies based on timing, subject matter, and factors outside your immediate control.

Whenever you see open rate displayed prominently on your platform’s dashboard, whether that is Mailchimp, ConvertKit, AWeber, or GetResponse, consciously treat it as background context at best, and let click through rate, click to open rate, and revenue per email drive your actual decisions instead.

Frequently Asked Questions

Is open rate completely useless now.

Not completely, but it should not be treated as a reliable, standalone measure of genuine engagement. It can still offer some very rough, directional signal at scale, particularly for lists with a smaller share of Apple Mail subscribers, but it should never be your primary metric, and any specific percentage figure should be treated with significant skepticism given the mechanism covered in this guide.

What is considered a good click through rate.

This varies significantly by niche, list size, and the depth of your relationship with your subscribers, which is why comparing your own click through rate against your own historical trend is generally more useful than comparing it against a generic, published industry benchmark. Focus on whether your own number is improving or declining over time relative to your own baseline.

How do I set up revenue per email tracking.

This generally involves adding UTM parameters to the links within your emails, allowing Google Analytics or your platform of choice to attribute resulting conversions or sales specifically back to that email send, combined with setting up defined conversion or goal tracking for whatever action represents revenue for your specific business, whether that is an affiliate link click through to a sale, or a direct product purchase.

Why does my open rate still look high if it is unreliable.

Because Apple Mail’s Mail Privacy Protection feature automatically triggers the tracking pixel for a large share of subscribers regardless of genuine engagement, which mechanically inflates the recorded open rate for any list with a meaningful proportion of Apple Mail users, which describes most consumer facing email lists to some degree.

Should I stop looking at open rate entirely.

Not necessarily entirely, but stop treating it as your primary or most important metric. It can still occasionally surface a genuinely useful signal, such as a dramatic, sudden drop that might indicate a deliverability problem, but click through rate, click to open rate, revenue per email, list growth rate, unsubscribe rate, and deliverability, covered throughout this guide, should be the metrics actually driving your decisions.

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• What Is Email Marketing, Why It Outperforms Every Other Channel
• How Blogging Makes Money, Every Revenue Stream Explained
• CPA vs CPS vs CPL vs Revshare, Affiliate Commission Models Compared

Final Thoughts

Open rate did not gradually become less useful over time. It broke at a specific, identifiable moment, in September 2021, when Apple changed how Mail app subscribers’ devices handle incoming email content, and most email marketing platforms simply kept displaying the same number, prominently, at the top of the same dashboard, without adequately signaling that its underlying meaning had fundamentally shifted.

Click through rate, click to open rate, revenue per email, list growth rate, unsubscribe rate, and deliverability, together, tell a far more honest, far more actionable story about what is genuinely happening with your list and your email program. None of them can be automatically inflated by a mail client quietly pre loading content in the background before a human being has ever actually seen the email at all.

Stop leading with open rate. Build your reporting habit around the numbers in this guide instead, and start making decisions based on what your subscribers are actually, genuinely doing, not what an automated privacy feature is doing on their behalf without their knowledge.