How to interpret your email marketing data without losing the will to live

Why should you care about your email marketing data?

Email is still one of the most useful digital channels available to a small business, particularly when you compare it with platforms where your reach can suddenly disappear because an algorithm has decided it would rather show everybody dancing dogs or entrepreneurs pointing at captions.

The useful thing about email is that you have a direct relationship with the people on your list.

But the numbers only become useful when you look at them in context.

One of the easiest mistakes to make is overreacting to a single metric. Maybe one email gets a lower open rate than usual. Five people unsubscribe. A campaign performs slightly worse than the one before it. Geoff in accounts announces that the header image “didn’t really grab him”.

None of those things tells you very much on its own.

Email performance is much easier to understand when you look for patterns and trends over time. One perfectly good email can underperform for all sorts of boring external reasons that have absolutely nothing to do with your strategy or ability.

So let’s look at the core email marketing metrics and what each one can actually tell you.

Open rate

Your open rate is the percentage of delivered emails recorded as having been opened.

The basic calculation is:

Number of opens ÷ number of delivered emails × 100

In practical terms, open rate gives you an indication of whether your sender name and subject line did enough to attract attention.

And that is pretty much where its usefulness ends.

It can’t tell you whether someone sat down with a cup of tea and read every word, skimmed it at a bus stop or accidentally opened it while trying to delete it.

There’s another complication too. Privacy changes such as Apple Mail Privacy Protection mean open rates aren’t completely precise anymore. Some opens are triggered automatically, some are inferred and some genuine opens may never be recorded.

So don’t treat your open rate as absolute proof that an email “worked”.

It’s much more useful as a comparative measure. Look at how different subject lines perform over time and pay attention if there’s a significant change across several campaigns.

A sudden sustained drop can also be a clue that you need to look at your email deliverability.

If you want to dig a bit deeper into what can affect whether your emails actually reach the inbox, have a read of our guide to email list hygiene and deliverability, which covers list health, sender reputation and the technical basics without making your eyes glaze over.

Click-through rate (CTR)

Click-through rate measures the percentage of delivered emails that generated a click.

The calculation is:

Number of clicks ÷ number of delivered emails × 100

This is one of the email marketing metrics I’d pay quite a lot of attention to.

A click tells you that somebody went beyond simply opening the email. Something inside it interested them enough to take action.

That might mean clicking through to your website, reading an article, looking at an offer, booking something or finding out more about a service.

High opens with very few clicks can suggest there’s a gap between what the subject line promised and what the email delivered. If people are opening but not clicking, the issue may sit with the content itself. Our guide to writing an email newsletter people actually want to open covers subject lines, structure, readability and giving each email a clear job.

Lower opens with decent click-through can sometimes mean that the email landed particularly well with a smaller, more engaged group.

If you only have the time or energy to keep a regular eye on a handful of figures, CTR deserves to be one of them.

Click-to-open rate (CTOR)

Click-to-open rate looks at the percentage of people who clicked after opening the email.

The calculation is:

Number of clicks ÷ number of opens × 100

This is useful because it helps separate two slightly different questions.

Did people want to open the email?

And once they opened it, did they find anything useful enough to act on?

If you’re getting healthy open rates but a weak CTOR, the issue may be sitting within the email itself. Perhaps the content didn’t quite live up to the subject line, the next step wasn’t clear or there simply wasn’t enough reason to click.

It’s a particularly handy metric when you’re trying to work out whether the problem sits at the inbox stage or inside the email.

Unsubscribes

Unsubscribes are exactly what they sound like: people choosing to stop receiving your emails.

And while watching somebody leave your list never feels especially lovely, it isn’t automatically a disaster.

A small amount of natural churn is completely normal.

People change jobs. Their interests change. They no longer need what you offer. Their inbox becomes unmanageable and they suddenly go on an unsubscribe rampage at 10pm on a Sunday.

That’s fine.

In the original article we used a rough benchmark of under 0.5% per campaign as perfectly comfortable territory, with an occasional figure closer to 1% not necessarily a reason to panic. The more useful thing to watch is the pattern.

A gradual trickle of unsubscribes is very different from a sudden spike.

If a lot more people start leaving than usual, look at what changed. Perhaps you’ve dramatically increased the sending frequency, shifted the type of content you send or become much more promotional.

Also remember that a smaller list full of people who genuinely want to hear from you is much more valuable than clinging desperately to thousands of disengaged subscribers.

Don’t be a needy Norman.

Spam complaints

Spam complaints happen when somebody actively marks your email as spam.

This one deserves more attention.

Even relatively small changes matter because spam complaints can directly affect your sender reputation and therefore the likelihood of future emails reaching people’s inboxes.

They’re often a sign that expectations have become mismatched somewhere along the line.

Maybe you’re emailing much more frequently than people expected. Perhaps they don’t remember signing up. Maybe your content has moved away from what they originally subscribed for, or it has become overwhelmingly sales-led.

The original article uses well below 0.1% as a sensible benchmark for spam complaints.

If you start seeing figures above that, look first at consent, expectations, relevance and frequency. Changing the colour of the button probably isn’t going to save you.

Other useful metrics worth checking

Your platform may also show you a few other useful figures.

Bounce rate tells you how many emails couldn’t be delivered. Regular bounces can indicate outdated or poor-quality email addresses and are one reason list hygiene matters.

Delivery rate gives you the opposite view, showing how successfully your emails were accepted for delivery.

Conversion data can be incredibly useful if your email platform connects properly with your website, ecommerce platform, forms or CRM. It allows you to see whether people went on to buy, enquire, register or complete another meaningful action.

The important word there is properly.

Half-configured conversion tracking can sometimes create more confusion than clarity. If you’re not confident in the setup, clicks may give you a more reliable starting point.

You don’t need to monitor everything obsessively. Pick the email marketing metrics that help you understand genuine behaviour rather than collecting numbers because the dashboard happens to display them.

So, which email metric matters most?

Annoyingly, the answer is: it depends.

If your aim is visibility or awareness, open rates and broader engagement trends can give you useful context.

If you want people to take action, CTR and conversion data matter more.

If you’re looking at the health of the mailing list, unsubscribes, spam complaints and bounces deserve your attention.

If you’re trying to understand whether the content itself is working, CTOR can be particularly revealing.

There isn’t one magic number that tells you whether your email marketing is good.

The useful insight comes from seeing how several metrics move together over time.

Ultimately, your data should help you answer some very ordinary questions: What’s working? What isn’t? What should we do more of? What could we stop doing?

That’s really what the dashboard is there for.