For years, open rate has been the first figure (and sometimes the only one) checked when reviewing an email marketing campaign's performance. The problem is that this metric, which was never perfect, has become notably less reliable since privacy features like Apple's Mail Privacy Protection started marking emails as "opened" that no one had actually read, simply because the mail system itself preloads the content automatically. Still only looking at that figure, in 2029, gives a fairly distorted picture of what is actually going on.
Why open rate no longer tells the whole story
When a significant percentage of recorded opens can be due to automatic preloading by the mail client itself rather than a real person consciously opening the email, comparing one campaign's open rate against another's (or against the industry average) becomes much less reliable than it was a few years ago. It should not be ignored entirely, it still gives some signal, but it should stop being treated as the main success metric.
Click-through rate (CTR): the metric that has gained relative weight
Click-through rate, meaning what percentage of recipients clicked on some link inside the email, is far harder to falsify or distort through automatic preloading systems, because it requires a deliberate action from the person. It is, by a wide margin, a more reliable indicator of real interest than a simple open, and deserves to be the main metric to pay attention to when comparing performance across campaigns.
Click-to-open rate (CTOR): a more nuanced view
Click-to-open rate (CTOR) measures what percentage of people who opened the email clicked on some link, instead of calculating clicks against the total number of recipients. This metric better isolates the quality of the email's content itself (once someone has already been persuaded to open it, is the content compelling enough to make them click?), separating it from the subject line and send time, which have the most influence on whether it gets opened at all.
Conversion rate: the metric that connects email to the real business
As with any other marketing channel, the metric that truly matters is what percentage of recipients ended up completing the desired action (a purchase, a booking, a download), not just opening it or clicking. To measure this precisely, the email marketing platform needs to be connected to Analytics or to the business's sales system, so the full journey from send to final conversion can be tracked.
Unsubscribe rate and spam complaint rate: the warning signs too easily ignored
A high unsubscribe rate on a specific campaign usually signals that the content or sending frequency does not match what the audience expects. Even more serious is the spam complaint rate, because a high volume of spam complaints can damage the sending domain's reputation with mail providers, hurting deliverability for all future emails, not just the specific campaign that generated the complaints.
Deliverability rate: the figure taken for granted without checking it
Many businesses assume that if an email "was sent", it reached the inbox. In reality, a percentage of sends can end up in the spam folder or bounce entirely without reaching anywhere, for reasons ranging from an outdated contact list to poor technical configuration of the sending domain (badly configured SPF, DKIM and DMARC authentication, for example). Checking deliverability rate periodically, not only when a problem is suspected, keeps this failure from going unnoticed for months.
Segmenting the analysis by campaign type and audience segment
Mixing an informational newsletter, a one-off offer campaign and a transactional email (an order confirmation, say) into the same report dilutes important patterns, because each type has a completely different expected performance. Likewise, analysing performance by audience segment (new customers versus returning customers, for example) usually reveals notable differences a combined report hides entirely.
An example of what CTOR reveals versus CTR
An online bookshop sent two campaigns the same week: one with the subject line "This week's new arrivals" and another with "The three best-selling books right now". The second had a considerably higher open rate, which at first glance suggested it was the winner. However, on checking CTOR (clicks over opens, not over total sends), the first campaign converted better among those who did open it, a sign that, although the subject line grabbed less initial attention, the content inside connected better with whoever ended up reading it. The practical conclusion was combining the best of both: using subject lines with the hook of the second campaign, while keeping the content structure of the first, which was the one actually generating clicks once inside the email.
Send time and day, a variable rarely tested
Many businesses always send their campaigns on the same day at the same time, out of habit or internal convenience, without ever having tested whether that time is really the best for their specific audience. Systematically testing different send days and times, with the same campaign, frequently reveals notable differences in opens and clicks that have nothing to do with the email's content itself, only with the moment it lands in each recipient's inbox.
Preview text, the forgotten ally of the subject line
Besides the subject line, most email clients show a snippet of preview text (preheader) right after or below the subject in the inbox. Letting that space be automatically filled by the email's first line (often "Can't see this email properly? View it in your browser", a completely wasted piece of text) throws away a second chance to convince someone to open the email. Writing that text deliberately, as a natural continuation of the subject line, usually improves open rate without needing to change the subject line itself.
Step by step: building a basic email marketing analytics dashboard
First, inside the email marketing platform (Mailchimp, Brevo, ActiveCampaign or similar), find the campaign comparison report, which usually shows every sent campaign with its main metrics in a single table. Second, add a manual column (or use the platform's tagging feature) to classify each campaign by type: informational newsletter, one-off offer, loyalty campaign, transactional. Third, calculate each campaign's CTOR (clicks divided by opens, not by total sends) if the platform does not do it automatically, and compare it within each category, never across different categories. Fourth, enable the automatic UTM tracking most platforms offer, and check in Analytics, once a month, how many sessions and conversions come specifically from the email channel. Fifth, identify the three best-CTOR campaigns of the last six months and note what they have in common (subject line type, length, send time, offer type), to replicate that pattern in future campaigns instead of starting from scratch every time. This basic dashboard, reviewed monthly, turns email marketing from an intuitive activity into one that measurably improves campaign after campaign.
Frequently asked questions
Should I stop looking at open rate entirely?
You do not need to ignore it completely, it still gives some approximate signal, but it should stop being treated as the main success metric, giving more relative weight to click-through rate and conversion rate.
What click-through rate is considered good in email marketing?
It varies a lot by industry and campaign type, so the more useful benchmark is not a generic industry figure, but comparison against the business's own history: whether click-through rate is improving or worsening compared to similar past campaigns.
How do I know if I have a deliverability problem without advanced technical tools?
An indirect signal is a noticeable, sustained drop in open rate across the whole list, not just one specific campaign, which can point to a growing share of sends ending up in spam. Most email marketing platforms offer some basic deliverability indicator without needing external tools.
Is it worth cleaning out contacts on the list who never open emails?
Yes, keeping long-inactive contacts on the list can hurt the sending domain's reputation and, with it, deliverability for all sends, so periodically pruning those contacts usually improves overall performance, even if it reduces the total list size.
Should I measure a transactional email (like an order confirmation) differently from a marketing one?
Yes, transactional emails naturally have much higher open rates because the recipient is actively expecting them, so comparing them directly against a newsletter or a promotional campaign gives a distorted picture of each type's real performance.
How do I connect my email marketing platform to Analytics to measure real conversions?
Most email marketing platforms let you add tracking parameters (UTMs) to links automatically, which lets Analytics identify which traffic and which conversions come specifically from each email campaign, without needing advanced technical setup.