Email platforms report two click metrics. Click rate is unique clicks divided by delivered emails, which shows how many recipients acted. Click-to-open rate (CTOR) is unique clicks divided by unique opens, meant to show how compelling the content was to people who opened it. Inflated opens from Apple Mail Privacy Protection distort CTOR, so click rate is often the steadier number.
The formulas
Click rate = Unique clicks / Delivered emails
Click-to-open rate = Unique clicks / Unique opens
Example: 240 clicks, 6,000 delivered, 1,800 opens
Click rate = 4%, CTOR = 13.3%Watch out for bot clicks
Corporate email security tools often scan links in incoming mail, which can register as clicks seconds after delivery. B2B lists are especially affected. Signs include clicks on every link in an email at once, or clicks before the email could plausibly have been read. Many platforms filter some of these, and some teams add a hidden link that only bots would click to identify them.
Making clicks meaningful
Clicks matter when they lead somewhere useful. Tag email links with UTM parameters so analytics and the CRM can see what readers did after clicking, and judge emails by the actions that follow: sign-ups, feature adoption, demo requests.
Example
Finding which link mattered
Hypothetical company Marrowfield’s product update email has a decent click rate, but UTM data shows most clicks went to a fun GIF, not the new feature. The next update leads with a single feature link and a short explanation, and adoption of that feature is tracked for the following week.
Common mistakes
Comparing CTOR before and after MPP
The denominator changed meaning in 2021. Long-term trends that cross that point need care.
Questions
The idea is similar, clicks divided by exposures, but the exposure differs: delivered emails rather than search impressions. Do not compare the numbers directly.
Report click rate as the main engagement figure, since its denominator is stable. Use CTOR as a secondary view of content quality, knowing that machine opens dilute it.
