Email Analytics
Email is the highest-ROI channel in marketing. For every $1 you spend, you get between $10 and $50 back on average (Litmus, 2024). But that average hides a massive range. The senders at the top track a small set of metrics obsessively. Everyone else sends and hopes. This lesson covers the exact numbers that separate the two groups: what each metric means, what moves it, and what to do when it goes the wrong way.
Quick Summary
- Seven core metrics cover everything you need: open rate, CTR, CTOR, conversion rate, unsubscribe rate, bounce rate, and revenue per email.
- Open rate is now unreliable. Apple Mail Privacy Protection (2021) inflates it for most senders. Use CTOR instead.
- Benchmark against your own past data, not industry averages. Industry averages mix too many different businesses to be useful.
- Your list shrinks naturally by about 22% per year. Regular cleaning protects deliverability.
- Revenue per email is the only metric tied directly to business outcomes. Track it every campaign, every segment.
What Is Email Analytics?
Email analytics is the practice of measuring, interpreting, and acting on data from your email campaigns and automation flows. The goal is not to hit a benchmark number. The goal is to understand which messages resonate, which segments respond, and which flows generate revenue, then use that to improve every future send.
Why email data is unusually reliable
Unlike social media (where an algorithm controls reach) or SEO (where Google can shift rankings overnight), email analytics measures things you directly control. You sent 10,000 emails. Exactly 4,200 opened. Exactly 210 clicked. That clarity is rare in marketing. Use it.
Why This Matters
- Deliverability depends on engagement. Gmail and Microsoft use engagement signals (opens, clicks, replies, and moving emails out of spam) to score your sender reputation. Low engagement causes future emails to land in spam, even for your best subscribers.
- Revenue attribution is unusually clear. With UTM tags (short tracking codes added to URLs) and ESP (Email Service Provider) revenue tracking, you can connect a specific campaign to a specific dollar on the same day.
- List decay is relentless. Email databases shrink by roughly 22% per year as people change jobs, abandon accounts, or lose interest (HubSpot, 2023). Without metrics, you will not notice the decay until your deliverability collapses.
- Automations need separate tracking. Welcome sequences, abandoned cart flows, and win-back campaigns behave very differently from one-time broadcast campaigns. Mixing their data together hides what is actually working.
The Seven Core Metrics
1. Open Rate
What it is: The percentage of delivered emails that were opened.
Formula: (Unique opens / Emails delivered) x 100
The problem with open rate: In September 2021, Apple launched Mail Privacy Protection (MPP). It pre-fetches emails in the background, registering an "open" even if the subscriber never actually reads the email. Senders with 40% or more Apple Mail users see heavily inflated numbers. According to MailerLite's analysis of 3.6 million campaigns (2025), the median open rate is now 43.46%, which sounds great, but is significantly inflated by MPP.
Use open rate as a directional signal only. If it drops suddenly, that is meaningful (possible deliverability issue). If it is consistently high, do not celebrate without checking CTOR too.
Healthy pre-MPP baseline: 20-35% for most B2C lists.
2. Click-Through Rate (CTR)
What it is: The percentage of delivered emails where someone clicked a link.
Formula: (Unique clicks / Emails delivered) x 100
What it tells you: CTR measures whether the email motivated action. A high open rate with low CTR means your subject line over-promised what the email body delivered.
Healthy range: 2-5% for marketing emails. Above 5% is strong. Below 1% means something is wrong with content, offer, or audience targeting.
According to MailerLite benchmarks (2025), the average CTR across all industries is 2.09%. Legal and manufacturing emails consistently outperform, reaching 4-5%.
3. Click-to-Open Rate (CTOR)
What it is: The percentage of people who opened the email AND then clicked something.
Formula: (Unique clicks / Unique opens) x 100
Why this is the most important engagement metric today: CTOR is largely immune to phantom opens. If Apple's system pre-fetches an email but the subscriber never sees it, no click follows. CTOR filters out that noise and measures genuine engagement among people who actually read the email.
According to MailerLite data (2025), the average CTOR is 6.81%. Aim for 10-15% as your own healthy baseline.
Healthy range: 10-20%. Above 20% is excellent.
4. Conversion Rate
What it is: The percentage of recipients who completed the desired action after clicking, purchase, sign-up, download, or whatever your goal was.
Formula: (Conversions / Emails delivered) x 100
What it tells you: Conversion rate connects your email to actual business results. It depends not just on the email but on the landing page it sends people to. A high CTR with low conversion usually means a landing page problem, not an email problem.
5. Unsubscribe Rate
What it is: The percentage of recipients who opted out after a specific email.
Formula: (Unsubscribes / Emails delivered) x 100
What is healthy: An unsubscribe is not always bad. It is cheaper to lose a disengaged subscriber via an opt-out than via a spam complaint. MailerLite reports the 2025 median unsubscribe rate at 0.22%.
Danger threshold: Above 0.5% per email means the message was irrelevant to that segment or you are sending too frequently.
6. Bounce Rate
What it is: The percentage of emails that could not be delivered.
Formula: (Bounced emails / Emails sent) x 100
Two types:
- Hard bounce: Permanent failure, address does not exist. Remove immediately. Continuing to send to hard bounces damages your sender reputation fast.
- Soft bounce: Temporary failure, inbox full, server down temporarily. Most ESPs (Email Service Providers) retry 3 to 5 times before converting a soft bounce to a hard bounce.
Healthy range: Below 2% total. Above 2% means you need a list hygiene review right now.
7. Revenue Per Email
What it is: Total revenue attributed to an email divided by the number of emails delivered.
Formula: Campaign revenue / Emails delivered
Why this is the metric that matters most: This connects your email program directly to the business. A campaign with a 40% open rate and $0.05 revenue per email underperforms one with a 20% open rate and $0.45 revenue per email. Track it per campaign, per automation flow, and per audience segment.
How Email Analytics Works: The Process
Real Company Results
Every Man Jack, 2024, predictive analytics driving 25% revenue growth
Every Man Jack is a personal care brand generating over $100M annually. They used Klaviyo's predictive analytics to find the exact moment each customer was likely running low on a product, then sent a reorder email with a pre-filled cart link timed to that moment.
Their old approach used a fixed 45-day trigger after purchase for everyone. The data showed that most customers actually needed 75 days. By switching to predicted next-order timing (calculated individually per customer), they achieved a 25% year-over-year increase in flows revenue in 2024.
The lesson: the same email sent at the right time for each person beats a universal timing rule every time.
Callie's Hot Little Biscuit, 2023, automation flows driving 157.8% YoY growth
Callie's Hot Little Biscuit, a handmade food brand, implemented 20+ email automation flows starting in June 2023. They set up loyalty triggers: a "Very Important Biscuiteer" status alert after a second purchase, and a free shipping offer after a third purchase.
Result: 157.8% year-over-year growth in email flows revenue within the first year.
Their approach treated analytics as the input that tells you when to send what to whom, not just what happened after the send.
Breaking Down Your Analytics
Aggregate numbers hide more than they reveal. Always break your data down by:
- Subscriber segment: New subscribers behave differently from customers who bought three times. Engaged subscribers are not the same as dormant ones. Never average them together.
- Flow type vs. broadcast: Automation flows (welcome, abandoned cart, win-back) run continuously and produce different engagement profiles. Keep them separate in your reports.
- Device type: Mobile open rates and click rates differ from desktop. A call-to-action button that converts at 5% on desktop may be too small to tap on a phone.
- Send day and time: Not to chase a generic "best time to send" (there is no universal answer), but to find your specific audience's pattern.
List Health: The Metrics Behind the Metrics
Beyond the seven core metrics, a healthy program also tracks these:
- List growth rate: (New subscribers, Unsubscribes, Bounces) / Total list size. A falling growth rate is an early warning sign even when engagement looks fine.
- Spam complaint rate: Keep this below 0.08% (Gmail's threshold) and 0.3% (Microsoft's threshold). Above these numbers, inbox placement drops automatically for everyone on your list, not just the complainers.
- Engagement score distribution: What percentage of your list opened or clicked in the last 30, 60, 90, and 180 days? A list where 70% of contacts have been silent for 90 days is a deliverability liability.
Never blast your full list to 're-engage' dormant subscribers
A common mistake when engagement drops: send a big re-engagement campaign to everyone who has not opened in 90 days. Doing this in one go causes a spike in spam complaints and can trigger a deliverability block from Gmail or Microsoft, harming your ability to reach your active subscribers too.
Instead: run re-engagement campaigns in small batches (no more than 10-15% of your inactive segment at a time), spread over several weeks. If a contact does not respond to a 3-email re-engagement sequence, remove them. Protecting deliverability for your engaged subscribers is worth far more than recovering a small fraction of dormant ones.
Your Benchmarks vs. Industry Averages
Industry benchmarks are useful only as a rough sanity check, never as a target. Numbers from Mailchimp, Klaviyo, or HubSpot average together wildly different businesses: a B2B SaaS newsletter, a retail flash-sale email, and a nonprofit donor campaign all count as "email." They have almost nothing in common statistically.
Set your own benchmarks: calculate your 12-month rolling average for each metric and track every new campaign against that. A 10% improvement in CTOR over your own baseline is more meaningful than hitting a generic industry average.
2025 industry medians for rough comparison (MailerLite, 3.6 million campaigns):
- Open rate: 43.46% (inflated by MPP, use directionally only)
- CTR: 2.09%
- CTOR: 6.81%
- Unsubscribe rate: 0.22%
Common Mistakes
- Optimizing subject lines using open rate after MPP. For subscribers using Apple Mail, open rate is partially fictional. Use CTR or CTOR as your primary A/B test metric.
- No UTM tags on email links. Without UTM parameters (tracking codes like
utm_source=email), revenue from email shows up as "direct" traffic in Google Analytics and becomes invisible for attribution. Every link in every email needs proper UTM codes. - Mixing automation and broadcast data in reports. Automation flows run continuously. Broadcast campaigns run in bursts. Their engagement profiles are totally different. Combining them produces averages that describe neither.
- Ignoring list decay. A list that was 25% engaged six months ago may be only 15% engaged today. Without regular engagement audits, you will not notice until your spam complaint rate suddenly spikes.
- Treating low unsubscribes as success. A low unsubscribe rate with a low CTOR means people are not leaving, but they are not clicking either. That is just a slower version of a dying program.
The one setup that pays for itself immediately
If you have not done this yet: add UTM parameters to every email link, and connect your ESP to Google Analytics 4. This lets you see exact revenue per campaign, per automation, and per segment, in the same place where you track all other marketing channels. Most ESPs (Klaviyo, Mailchimp, ActiveCampaign) have a native GA4 integration that takes 10 minutes to set up.
The One-Line Takeaway
Track CTOR and revenue per email by segment on every send, these two numbers cannot lie to you, even when open rates can.
