Email Marketing Metrics That Actually Matter (And Ones You Can Ignore)
The Metrics Hierarchy
Not all email marketing metrics are created equal. Some drive real business decisions. Others look impressive in slide decks but lead you astray. After two decades of watching marketers obsess over the wrong numbers, we’ve developed a clear hierarchy that separates the metrics that matter from the ones that mislead.
The hierarchy, from most to least actionable: Revenue per email > Conversion rate > Click-through rate > Click-to-open rate > Open rate > List size. If you’re spending more time celebrating list growth than tracking revenue per subscriber, you’re driving by looking in the rearview mirror.
The Metrics That Drive Revenue
Revenue Per Email (RPE)
This is the north star metric. Total email-attributed revenue divided by total emails sent (or sometimes by total subscribers). RPE tells you, in concrete dollars, what each email is worth to your business.
A healthy ecommerce email program generates $0.08 to $0.15 per email sent. Top performers reach $0.25 or higher. If your RPE is declining month over month, something fundamental is wrong — even if your open rates look fine.
RPE also enables the most important calculation in email marketing: the value of a subscriber. If your RPE is $0.10 and you send 12 emails per month, each subscriber is worth $1.20/month or $14.40/year. That number determines how much you can rationally spend on list building, and most marketers vastly overspend or underspend because they’ve never calculated it.
Conversion Rate
The percentage of email recipients who complete a desired action: purchase, signup, download, registration. This is where email meets business outcomes.
Average email conversion rates hover around 1-5%, depending on industry and what counts as a “conversion.” Abandoned cart emails are the high performers here — Klaviyo reported in 2023 that automated abandoned cart flows convert at 3.33% on average, dramatically outperforming broadcast campaigns.
Track conversion rate by email type, not just overall. Your weekly newsletter, your promotional blasts, and your automated sequences will have wildly different conversion profiles, and that’s expected.
Click-Through Rate (CTR)
CTR measures the percentage of recipients who clicked at least one link in your email. The industry average sits around 2.5-3.5%, though this varies significantly by sector. Government and nonprofit emails tend to see higher CTRs (around 4-5%), while retail often falls below 2%.
CTR is the first metric in our hierarchy that directly measures recipient behavior rather than business outcomes. It answers a crucial question: “Did the email compel action?” A high open rate with a low CTR means your subject line works but your content or offer doesn’t. That’s a valuable diagnostic signal.
One technical note: distinguish between total clicks (every click, including multiple clicks from the same person) and unique clicks (one click per person regardless of how many times they clicked). Unique CTR is the more honest metric.
Click-to-Open Rate (CTOR)
CTOR divides unique clicks by unique opens. Where CTR measures clicks against total recipients, CTOR measures clicks against the people who actually saw your email. It isolates your email content’s persuasive power from your subject line’s ability to drive opens.
A good CTOR ranges from 10-15%. If your CTOR is high but your overall CTR is low, your content is working — you just need more people to open. If your CTOR is low but your open rate is high, your subject line is writing checks your email body can’t cash.
CTOR has become more useful since Apple’s Mail Privacy Protection (MPP) muddied open rate data in 2021. Since MPP artificially inflates opens, CTOR based on those inflated numbers can be misleading. Some teams now calculate CTOR only from non-Apple opens for a cleaner signal.
The Metrics That Inform (But Don’t Drive)
Open Rate
For two decades, open rate was the king of email metrics. Marketers lived and died by it. Then in September 2021, Apple released iOS 15 with Mail Privacy Protection, and the crown fell off.
MPP pre-loads tracking pixels for Apple Mail users regardless of whether they actually read the email. Since Apple Mail accounts for roughly 50-60% of email opens in many consumer lists, open rates became significantly inflated. A “true” open rate of 22% might display as 35% or higher when Apple devices are included.
Open rate still has value as a relative metric. If Campaign A shows a 28% open rate and Campaign B shows a 19% open rate (same list, same timeframe), you can reasonably conclude that A’s subject line performed better. But the absolute number is no longer trustworthy for benchmarking.
Use open rates for A/B testing subject lines and optimizing send times. Do not use them to evaluate overall program health. That’s RPE’s job.
List Size
The most dangerous vanity metric in email marketing. A list of 100,000 unengaged subscribers is worth less than a list of 5,000 people who actually read your emails and buy things.
List size matters only in relation to engagement. Track engaged subscribers (those who have opened or clicked in the last 90 days) separately from your total list. Most experienced marketers find that 20-40% of their list is truly engaged at any given time, and that’s normal.
The obsession with list size leads to the single most common mistake in email marketing: refusing to remove inactive subscribers. Dead weight on your list actively harms deliverability. ISPs monitor engagement ratios, and a list full of people who never open your emails signals to Gmail and Outlook that your content isn’t wanted. Use our ROI Calculator to model how a smaller, engaged list can outperform a bloated one.
The Metrics That Protect Your Program
Bounce Rate
Bounces come in two varieties. Hard bounces mean the address doesn’t exist — it’s invalid, closed, or was never real. Soft bounces are temporary failures — full mailbox, server timeout, message too large.
Keep your hard bounce rate below 0.5% per campaign. Above 2%, you have a list hygiene crisis. Major ESPs like Mailchimp, SendGrid, and Brevo will suspend your account if bounce rates stay elevated because high bounces damage their shared sending infrastructure.
Spam Complaint Rate
When a recipient clicks “Report Spam” or “Mark as Junk,” that registers as a complaint. Google’s 2024 sender requirements set a hard ceiling: complaint rates must stay below 0.3%. In practice, you should target below 0.1%.
Complaint rates above 0.1% trigger reputation damage that takes weeks to recover from. Every complaint is a signal to inbox providers that your emails are unwanted, and those signals carry outsized weight in spam filtering algorithms.
Common causes of high complaint rates: unclear opt-in process, emails that look different from what was promised, sending too frequently, and making the unsubscribe link hard to find. The last one is counterintuitive but critical — when people can’t easily unsubscribe, they use the spam button instead, which is far more damaging to your reputation.
Unsubscribe Rate
A healthy unsubscribe rate is 0.1-0.5% per campaign. Unlike spam complaints, unsubscribes are not inherently bad. A person unsubscribing is a person self-selecting out of your audience, which improves your engagement ratios and protects your sender reputation.
Worry about unsubscribe rates only when they spike suddenly (indicating a content or frequency problem) or when they stay consistently above 1% (indicating a list quality or expectation-setting problem).
Building Your Metrics Dashboard
We recommend tracking these metrics at three levels:
Per-campaign level: Open rate, CTR, CTOR, unsubscribes, bounces, complaints. These diagnose individual email performance.
Monthly program level: RPE, conversion rate, list growth rate, engaged subscriber percentage. These measure program health.
Quarterly business level: Revenue per subscriber (annualized), customer lifetime value from email, email’s share of total revenue. These justify your email marketing investment.
Most email platforms — Mailchimp, Klaviyo, ActiveCampaign, ConvertKit — report per-campaign metrics automatically. The monthly and quarterly metrics usually require pulling data into a spreadsheet or dashboard tool, combining email platform data with revenue data from your ecommerce platform or CRM.
The goal is not to track everything. The goal is to track the right things, at the right cadence, and make decisions based on what actually moves revenue. Everything else is noise.
Frequently Asked Questions
What is a good email open rate?
The industry average is 21-25%, but this varies widely by sector. B2B typically sees 20-23%, while media and publishing can reach 25-30%. Important caveat: Apple Mail Privacy Protection inflates open rates by pre-loading tracking pixels, so the metric is less reliable than it once was.
What email metric is most important?
Revenue per email (or revenue per subscriber) is the most important metric because it directly ties email performance to business outcomes. Open rates and click rates are useful for optimization, but revenue is what matters. If your emails generate money, the other metrics are just tools to make more.