Measuring and optimizing: steering instead of guessing

Without measurement, you send blind

Email is one of the most measurable channels there is: you know who opens, who clicks, who unsubscribes, who buys. Yet many entrepreneurs send without ever looking at the numbers, then conclude on a hunch that "email works" or "doesn't work". That wastes the channel's main advantage. Measuring isn't about producing reports: it's about knowing what to improve first, and to stop guessing. Each metric points to a precise link in the chain that's leaking.

Email numbers aren't a report card, but a map: they show where on the journey you're losing people, hence where to act.

The metrics that really matter

Not all dashboard numbers are equal. The essentials, and what they reveal:

The open measures the appeal of the envelope; the click measures interest in the content; the conversion measures real value. It's the conversion that pays the bills.

Reading an open rate without fooling yourself

The open rate is the most-watched metric — and the most misleading. First, it has become approximate: privacy protections (like Apple Mail Privacy Protection) artificially inflate opens by preloading images. Second, an open without a click isn't worth much: the envelope was seen, no action taken. The healthy reflex: track the open as a trend (rising or falling over time), not as an absolute value, and give more weight to the click rate and conversions, which are harder to skew. A subject line can raise the open without changing sales: only clicks and purchases settle it.

The A/B test: deciding by data

Rather than debating the best subject line, you test it. The A/B test sends two versions (two subject lines, two calls to action, two send times) to subgroups, measures which wins, and applies the winner. Most ESPs build it in. Two rules to make it reliable: test only one variable at a time (otherwise you don't know what made the difference), and only conclude on sufficient volumes — on 30 sends, the gap is just chance. Done well, the A/B test replaces opinions with decisions, and every send becomes a learning.

The compass: LTV, cost and revenue per subscriber

To steer a business, the ultimate metric isn't the open but what email earns. Two useful benchmarks. Revenue per subscriber (revenue generated ÷ number of subscribers) tells you what your list is really worth, and whether it's improving. And comparing the value of a subscriber (what they earn over time) with the cost to acquire them (ads, lead magnet, tools) tells you whether your collection is profitable. It's the same compass as everywhere in business: what a contact earns must exceed what they cost. A big list that earns nothing is worth less than a small list that buys.

From dashboard to decision

Measuring is useless if it doesn't change an action. The method comes down to a simple loop: spot the weakest link in the numbers, form a hypothesis, test a change, measure the effect. Low opens? Work on subject lines and deliverability. Good opens but few clicks? Revisit content and call to action. Rising unsubscribes? Reduce frequency or target better. Many bounces? Clean the list. You fix one link at a time, you measure, you start again — rather than changing everything at once without knowing what worked.

Key takeaways

Email is very measurable, and measuring serves to know what to improve first, not to make reports. Track the metrics that matter: open (as a trend, since it's skewed), click and especially conversions/revenue, without forgetting unsubscribes, bounces and complaints. Decide by A/B test — one variable at a time, on sufficient volumes. Keep as your compass the revenue per subscriber and the ratio between a contact's value and cost. Then turn every number into action via a simple loop: spot the weak link, test, measure, repeat. All that's left is to connect all these links into a coherent system: let's assemble the stack.