Click Rate vs. Click-to-Open Rate
Two ways to measure clicks — one out of everyone who got the email, one out of only the people who opened it.
What it means
Click rate (CTR) is clicks divided by emails delivered. Click-to-open rate (CTOR) is clicks divided by emails opened — it asks "of the people who opened this, how many clicked?" instead of "of everyone who got this, how many clicked?"
Why it matters
Since open rate is inflated by Apple's automatic opens, CTOR is also skewed by the same problem — the denominator includes people who never really saw the email. Click rate, using total delivered as the denominator, is steadier and usually the better number to trust when comparing campaigns over time.
ask datanephew
Which number should I actually pay attention to?
Ask datanephew for click rate first — it is less affected by inflated opens. Use click-to-open rate mainly to compare subject lines against each other, not as an absolute measure of health.
Did my new email design actually get more clicks?
Ask datanephew to compare click rate across the campaigns before and after the redesign — that tells you whether the content itself is landing better, regardless of open-tracking noise.