Email Marketing Metrics: What to Track and What Numbers Are Normal

You sent a campaign. Open rate came in at 18%. Good or bad? CTR at 2.4% — is that a win or a miss? Without context, the numbers mean nothing. Below are all the metrics worth tracking, with concrete industry benchmarks.

Why bother measuring at all

Metrics tell you whether a campaign is working. Without them you are flying blind. You can spend months sending emails that nobody reads and have no idea. Or you can panic over a "low" open rate that is actually above average for your industry.

The trap, though, is tracking everything. Twenty charts on a dashboard paralyze rather than inform. What follows covers only the numbers that actually drive decisions — nothing else.

Open rate: how many people opened

Open rate is the percentage of delivered emails that were opened. Formula: (opens / delivered) × 100%.

Since 2021 this metric has become less reliable. Apple Mail Privacy Protection pre-loads emails automatically, recording an "open" even when the person never read it. Depending on how many Apple users are in your list, this inflates open rate by 5-15%. The metric is still useful for comparing campaigns against each other, but treat absolute values with caution.

Open rate benchmarks by industry (2025-2026):

An open rate below 15% is a problem in any industry. The usual culprits: a weak subject line, deliverability issues, or dead addresses diluting your list.

CTR: who clicked

Click-through rate is the percentage of recipients who clicked at least one link. Formula: (unique clicks / delivered) × 100%.

CTR is more reliable than open rate. A click cannot be faked by a pre-loader — if someone clicked, they actually engaged with the email. That is why many marketers treat CTR as the primary engagement metric in 2026.

CTR benchmarks by industry:

CTR below 1% is a warning sign. Either the content misses what your audience cares about, or there is no clear call to action, or your links are buried where nobody finds them.

CTOR: engagement among openers

Click-to-open rate is the percentage of people who clicked among those who opened. Formula: (unique clicks / unique opens) × 100%. Typical range: 10-17%. Above 20% is solid.

CTOR answers a specific question: once someone opened the email, did they find anything worth clicking? If open rate looks fine but CTOR is low, the problem is inside the email itself — the content, the layout, or where the buttons are placed.

Bounce rate: undelivered mail

Bounce rate is the percentage of emails the receiving server rejected. Two types: hard bounce means the address does not exist, the mailbox was deleted, or the domain is dead — remove these immediately. Soft bounce is a temporary failure: full inbox, server down. Give it three attempts, then archive.

• Below 2% — normal. Your list is clean.
• 2-5% — yellow zone. Time to run a validation.
• Above 5% — red flag. Your ESP may throttle sending and your domain reputation is at risk.

Based on our data, the average list loses 20-25% of valid addresses per year. People change jobs, switch email providers, abandon free accounts. If you have not validated your list in six months, the bounce rate on your next campaign will likely surprise you.

Unsubscribe rate: who is leaving

The percentage of recipients who clicked "Unsubscribe." Formula: (unsubscribes / delivered) × 100%. Normal is under 0.5% per send. For new lists or after a long sending gap it can hit 1%. Above that consistently means something systemic is wrong: too-frequent sends, irrelevant content, or subscribers who never expected to be on your list.

Counterintuitively, an unsubscribe is not the worst outcome. Worse is when someone skips the unsubscribe link and hits "Report spam" instead. A spam complaint damages your domain reputation far more than a clean opt-out. Make the unsubscribe link visible and one-click. Losing a subscriber cleanly beats earning a complaint.

Spam complaint rate: the dangerous one

The percentage of recipients who marked your email as spam. The threshold where problems start: 0.1%, meaning one complaint per thousand delivered emails. Google states this number explicitly in its sender guidelines. Sustain a rate above it and your campaigns will start getting filtered.

Monitor complaints via your ESP's feedback loop (FBL) or Google Postmaster Tools. If the rate is climbing, first check whether you are mailing people who never gave consent. Then confirm the unsubscribe link works.

Conversion rate: the money metric

The percentage of recipients who completed a target action: a purchase, registration, or form fill. It varies by industry, email type, and offer. Triggered emails — abandoned cart, welcome series — convert 3-5x better than broadcast campaigns.

Typical ranges: broadcast promo 0.5-2%; welcome series 2-5%; abandoned cart 3-8%; re-engagement series 0.5-3%.

Tracking conversions requires connecting your email platform to analytics: UTM parameters on links, Google Analytics or a CRM. Without that connection, you see clicks but not sales.

ROI: does email pay off

Return on investment. Formula: ((email revenue - costs) / costs) × 100%. According to Litmus (2024), the average email marketing ROI is $36 per dollar spent, one of the highest figures across all marketing channels.

The average is misleading, though. A company with a clean list, proper segmentation, and working triggers can reach 50:1 or better. A company sending one blast a month to a stale list might see 5:1 on a good day. That ten-fold gap comes down to list hygiene, not creative.

Email ROI is determined by infrastructure: a clean list, proper authentication, regular validation.

List growth rate: is your list growing

How fast your subscriber list grows. Formula: ((new subscribers - unsubscribes - removed) / list size) × 100%. Healthy: 2-5% per month. Negative growth is not automatically bad — after scrubbing invalid addresses, a list can shrink 15-25% while quality improves. The real warning sign is losing subscribers faster than you gain them.

Delivery rate and inbox placement rate

Delivery rate is the percentage of emails the receiving server accepted. Normal: above 95%. Below 90% means a serious infrastructure or reputation problem. But delivery rate is not the same as inbox placement. A server can accept an email and route it straight to spam. Inbox placement rate (IPR) shows what percentage actually landed in the inbox — measure it via seed testing with GlockApps or 250ok. Target: above 85%.

Revenue per email (RPE): income per send

For e-commerce, this metric matters more than open rate and CTR combined. Formula: email revenue / delivered emails. RPE shows how much each sent email earns. Typical figures for online retailers: $0.05-0.20 per email for broadcast sends and $0.50-2.00 for triggered emails (abandoned cart, post-purchase).

RPE is directly tied to list quality. Dead addresses add to the denominator (delivered) without contributing to the numerator (revenue). After a list cleanup, RPE typically rises 30-50% with no changes to the email itself.

Summary table: all metrics and thresholds

How metrics connect to list quality

We see the same pattern repeatedly. A client reports low open rate and CTR. We look at the list — not cleaned in a year. 18% of addresses are invalid; another 12% are inactive mailboxes that technically exist but nobody checks. After validation, open rate rises 20-40% and CTR follows. The content did not change. What changed is that metrics stopped being diluted by addresses that would never open anything.

There is also a cascade effect. A clean list improves domain reputation. Better reputation improves inbox placement. Better inbox placement raises open rate. Each step feeds the next.

What to track first

If you are starting out, do not try to monitor ten metrics at once. Priority order:

• Bounce rate. The list health indicator. High bounce distorts everything else — fix it with validation before anything else.
• Spam complaint rate. The only metric that can shut your channel down entirely. Sustain above 0.1% and Gmail routes all your mail to spam.
• CTR. Shows whether content is working. Below 1% consistently means the content, offer, or format needs to change.
• Conversion rate / RPE. Once the basics are healthy, shift focus to revenue. Which sends actually earn?
• Open rate. Fifth on the list. Useful for A/B testing subject lines, but too noisy after Apple MPP for absolute benchmarking.

Common mistakes when reading metrics

Benchmarking against other industries. Benchmarks are reference points, not targets. A niche B2B product with 3,000 subscribers seeing 35% open rate is completely normal. An online retailer with 200,000 subscribers hitting the same number would be an anomaly. Compare your current campaigns against your own past results, not some abstract industry average.

Judging from a single send. One campaign is not data. Day of the week, seasonality, subject line — everything affects individual results. Look at monthly and quarterly trends. A 3% drop in open rate on one send is noise. Three consecutive months of decline is a problem.

Ignoring segments. An average open rate across your whole list is close to meaningless. An active segment might deliver 40%; a dormant one, 3%. The blended number reads as a "normal" 20%, but you are actually looking at two different audiences that need two different approaches. Always break metrics down by segment.

Practical checklist

• Run your list through a validator and remove invalid addresses. This alone lowers bounce rate and lifts every other metric.
• Configure your ESP to track bounce rate, CTR, unsubscribe rate, and complaint rate on every send.
• Add UTM parameters to all links so conversions show up in Google Analytics or your CRM.
• Compare metrics by segment, not across the whole list.
• Analyze trends monthly. Do not react to single-campaign fluctuations.
• Run a seed test for inbox placement rate at least once per quarter.

Metrics only matter if they lead to action. Bounce rate too high? Validate the list. CTR stalling? Rethink the content. Complaint rate rising? Check whether those subscribers actually consented. Every number should point to a specific next step. If you are staring at a dashboard and do not know what to do next, you are probably tracking the wrong things.