Email Marketing Metrics: What Each Number Tells You

Most owners I talk to check their results, feel their stomach drop a little, and rewrite the subject line. That only helps when opens are the problem. Here's the list I work through instead, the same one from my Instagram Reel.

What do your email numbers tell you to fix?

Each email number points at a different part of the journey. Opens tell you about the inbox. Clicks are about the email itself, and sales happen on the page people land on. Find your weakest number, fix that one thing, and leave the rest alone until it moves.

One warning first. Apple Mail Privacy Protection loads emails automatically, which inflates open rates. About 51% of tracked opens are affected (yocto.agency). So I judge an email mostly on clicks and sales. I use Klaviyo below, but Mailchimp, Omnisend and Shopify Email report most of these too.

Weak opens? Test your subject line and preview text

If your opens are low, test new subject lines and preview text. For example:

Why it works: people decide whether to open in about a second, and phones and AI inbox summaries cut everything after the first few words. "October newsletter" tells them nothing. The second version says what they get, straight away. Put the value in the first 20 characters, because specific beats curious (Salesforce). The preview text (the grey line after the subject) is your second chance, so don't waste it on "Read more inside".

How to do it: in Klaviyo, set up an A/B test on your next campaign. Two subject lines go to a small slice of your list, and the winner goes to everyone else. Change one thing at a time, and judge the winner on clicks, not opens. Apple Mail Privacy Protection opens emails automatically, and about 51% of tracked opens are affected (yocto.agency), so a low open rate is an even louder warning than it looks. If opens drop on every email at once, the subject lines probably aren't the problem. Skip down to deliverability.

Where to find it: the open rate on each campaign and flow email report.

Weak clicks? One clear button

If your clicks are low, give each email one clear button. For example:

Why it works: every extra link is another decision, and decisions slow people down. One job per email means one obvious thing to do. Buttons also beat text links by 28% (conversion.studio), because a button looks like something to tap. A text link looks like part of the sentence.

How to do it: decide the one thing this email is for before you write it. Put a short reason just above the button (why this, why now), make the button your brand colour and big enough for a thumb, and say exactly what happens when they tap. Keep the email short. The best performers sit around 50 to 125 words (conversion.studio).

Where to find it: click rate on each email. The ecommerce average is 1.69% for campaigns and 5.58% for flows (threadpoint.agency, 2026), but your own past emails are the fairer comparison.

Weak deliverability? Clean your list and verify your domain

If your deliverability is weak, clean your list and verify your domain. For example:

Why it works: Gmail, Yahoo and Outlook watch how people react to your emails. Every email sent to someone who never opens it tells them you're not worth the inbox, and that drags down delivery for everyone else on your list. Verification proves the emails really come from you. Google, Yahoo and Microsoft now enforce these rules for bulk senders, and breaking them can mean outright rejection, not just the spam folder (courier.com; autospf.com).

How to do it: set up a sunset flow. Anyone inactive for 90 to 120 days gets two or three final emails ("still want to hear from me?"), and if they don't respond, you stop sending to them. Then check your domain. In Klaviyo, set up a branded sending domain, make sure DKIM passes and DMARC is set to at least p=none, and keep SPF under 10 DNS lookups. Those three names (SPF, DKIM and DMARC) are settings in your domain, and whoever manages your website or email can set them up in an afternoon.

Where to find it: bounce rate and spam complaints on each send, Klaviyo's deliverability reporting, and Google Postmaster Tools for Gmail.

Weak sales? Fix the page they land on

If people click but don't buy, fix the page they land on. For example:

Why it works: a click means the email did its job. People wanted the thing, and the page made them work to find it. Click-to-conversion rates rose 53% year on year to 9.0% (webtonic.io). People click less often now, but when they do, they arrive ready to buy. A weak landing page wastes your best visitors.

How to do it: link every button to the exact product or service in the email, never the homepage. Match the page's headline and image to the email, so it feels like the next step rather than a new start. Show the price, shipping and next step without scrolling. Then click through your own email on your phone and try to buy. You'll find the snag faster than any report will.

Where to find it: compare each email's click rate with its placed order rate in Klaviyo, then check that landing page in Google Analytics 4 (GA4).

Not sure which of these is your weak one? That's exactly what my free Keep Check is for. I go through your emails properly, then send you a short video and a one-page Spring Back Plan with the three fixes that matter most, within 3 working days.

Weak flow revenue? Build your welcome and abandoned cart emails

If most of your email revenue comes from campaigns, build welcome and abandoned cart emails. For example:

Why it works: flows (automated emails triggered by what someone does) arrive at the moment people are most interested. Klaviyo's 2026 benchmarks put flows at 41% of email revenue from just 5.3% of sends. The average flow placed order rate is 2.11%, against 0.16% for campaigns (threadpoint.agency; Klaviyo). Flows also keep working while you sleep.

How to do it: start with two. The welcome series sends the promised offer straight away, your story on day 2, then reviews and best sellers on day 4. The abandoned cart flow sends a gentle reminder after 2 to 4 hours (no discount), a nudge at 24 hours, and an alternative or a reason to act at 48 hours. For a service business, abandoned cart becomes a follow-up for anyone who starts an enquiry or booking and doesn't finish.

Where to find it: Klaviyo splits email revenue between campaigns and flows in its dashboard.

High unsubscribes? Send less, or send to the right people

If your unsubscribes spike, send less or segment your list. For example:

Why it works: people rarely unsubscribe because of one email. They leave because there are too many, or because what you send doesn't fit them. Segmenting just means splitting your list by what people bought or did, and sending each group what's relevant to them.

How to do it: compare each campaign's unsubscribe rate with your own average, and look at what the spikes have in common. Cut frequency first, because it's the quickest test. Then build two or three simple segments, such as recent buyers, people who've never bought, and past customers who've gone quiet. Don't fear every unsubscribe, though. Someone leaving quietly beats someone reporting you as spam.

Where to find it: unsubscribe rate on each campaign. Watch for spikes against your own average.

High spam complaints? Make unsubscribing easy to find

If your spam complaints climb, make unsubscribing easy to find. For example:

Why it works: when leaving looks hard, people tap "report spam" instead, and that hurts you far more than an unsubscribe. Keep your spam complaint rate under 0.3%, and aim for under 0.1%. Above 0.3%, inbox providers start penalising your domain (mailpro.com; chronos.agency).

How to do it: make the unsubscribe link readable, not hidden, and check it works in one click. Klaviyo does one-click unsubscribe by default, so confirm it on other platforms. Pair it with the sunset flow above, so people who've gone quiet get a polite way out before they get annoyed. In Australia, the Spam Act 2003 requires a working unsubscribe in every commercial email anyway.

Where to find it: spam complaint rate on each send.

Email numbers at a glance

Which email number should you fix first?

Fix the number closest to the money. For most small businesses that's flow revenue, because Klaviyo's 2026 benchmarks put flows at 41% of email revenue from only 5.3% of sends. If your flows are already built, work down the list from clicks, because that's where most emails lose people.

Then go one at a time. Change one thing, give it a few weeks and check the same number again. Change five things at once and you'll never know which one worked. I check campaign numbers after every send and look at flows once a month.

Want a second pair of eyes? My free Keep Check looks at your email and SMS from the inside: your welcome emails, follow-ups, campaigns and the setup underneath. Within 3 working days you'll get a short video from me and a one-page Spring Back Plan with the three fixes that matter most.

Website not getting enquiries either? Read the website version of this guide.