Open your email tool and you are hit with a wall of stats — opens, clicks, bounces, rates, ratios. Most of them are vanity or noise, and chasing all of them is a good way to feel busy while learning nothing. The point of a metric is to change what you do next.
A short list of numbers tells you almost everything worth knowing. Here they are, and what each one is actually saying.
The numbers worth watching
Track a handful, and read them as questions about your emails, not as scores to feel good or bad about.
- Click rate — did the email make people act? The truest engagement signal.
- Conversions — how many actually bought, booked, or signed up. The one that pays.
- Unsubscribe and spam rate — a spike means you pushed too hard or sent junk.
- List growth — is your audience getting bigger than it is shrinking?
Why open rate lies more than it used to
Open rate feels like the headline number, but it has quietly become unreliable — privacy features on many devices now mark emails as opened whether or not anyone read them. It is a loose directional hint, not a fact. Treat a sudden drop as worth a look and a steady figure as barely news.
Clicks are harder to fake. Someone who clicks actually did something, which is why click rate beats open rate for judging what your readers want.
Connect the email to the money
The metric almost nobody sets up and everyone should is what happens after the click. Opens and clicks are means; sales, sign-ups, and bookings are the end. If an email got great opens and zero purchases, it did not work — no matter how the top-line stats look.
Always trace the chain back to a real outcome. That is the difference between measuring activity and measuring results.
Watch trends, not single sends
One email is too small a sample to teach you much — a good subject or a slow day can swing it. Watch the direction over many sends: are clicks and conversions rising as you improve, or drifting down as the list goes stale?
You can see how your emails, forms, and sales connect in one place at onesol.io, so you are measuring outcomes, not just opens.
Why Open Rate Lies to You Now
Open rate used to be the headline number, and it's now the least trustworthy one. Apple's Mail Privacy Protection, on by default for anyone reading in Apple Mail, pre-loads the invisible tracking pixel whether or not the person actually opened the email. That inflates your open rate with phantom opens and can push it past a hundred per cent on some sends, which tells you nothing real.
This doesn't make open rate useless, but it demotes it from a metric to a rough trend line. Watch whether it's drifting down over months — a genuine slide can still signal fatigue or a deliverability problem — but don't celebrate a 60% open or panic at a 30% one, and never settle a subject-line test on opens alone, because a large chunk of your audience is counted as 'opened' no matter what you wrote.
The practical move is to stop treating opens as proof anyone read anything, and to stop reporting them to yourself as if they were sales. They're a weak proxy at best now. What people actually did with the email — the part that matters — lives further down the report.
Follow Clicks, Replies, and Revenue Instead
A click is someone deliberately choosing to act, which is worth a hundred passive opens. Track your click rate on the link that matters — the product, the booking page, the thing you actually wanted them to do — rather than a total that lumps in the unsubscribe link and your Instagram handle. If 40 people out of 1,000 clicked through to the product, that's a real, countable signal you can improve week to week.
Replies are rarer and even more telling. When you ask a question and people answer, you're seeing genuine engagement and, as a bonus, teaching mailbox providers you're a real correspondent. And revenue per subscriber quietly settles most arguments: total sales from an email divided by how many people received it. An email to 1,000 people that earns £500 is worth £0.50 a head — compare that across sends and you learn which topics actually pay, not just which get looked at.
These are the numbers to write down after each send. A short running note — clicks on the main link, replies, and pounds earned per subscriber — tells you more in three lines than a dashboard of twenty vanity metrics, and it points directly at what to do more of next time.
Read Unsubscribes and Spam Complaints as Feedback
Unsubscribes feel like rejection, but a low, steady rate is healthy — it's the list cleaning itself of people who were never going to buy, which improves both your deliverability and your true engagement rate. A sudden spike, though, is a message: something in that email — the tone, the frequency, a hard sell out of nowhere — didn't match what people signed up for. Read the spike, don't just wince at it.
Spam complaints are the serious one to watch. Where the occasional unsubscribe is fine, complaints should be vanishingly rare, because each one tells Gmail your mail is unwanted and a cluster can push your whole list into the spam folder. If complaints climb, you're almost always mailing people who forgot they signed up, mailing too often, or hiding the unsubscribe link where they can't find it.
- Unsubscribes: a low, steady rate is normal and healthy
- A sudden unsubscribe spike: check that email's tone or frequency
- Spam complaints: should be extremely rare — treat any rise as urgent
- Both climbing at once: you're probably mailing too often