Open Rate · Click-Through Rate (CTR)
Open Rate · Click-Through Rate
What is open rate?
- Open rate = the subject line's score, CTOR = the body's score
- Since Apple MPP, use open rate only for trends and comparisons
- Judge success by clicks and what follows
Once you look at open rate and click rate separately, the language in your meetings changes. Instead of a vague 'this issue didn't do well,' you pinpoint the stage: 'it was sent, but got stuck at the subject line' or 'they opened it, but left at the body.' That also settles whether next week's target is a single subject line or a single CTA button. The moment you split the metric, the improvement work splits too. If you can't identify the culprit, you'll keep overhauling the entire newsletter every month for nothing.
In practice, half the battle is checking the denominator. CTR is clicks divided by sent (or delivered), while CTOR is clicks divided by opens, so a campaign with a 30% open rate and 3% CTR has a CTOR of 10%. Look at delivery-stage metrics too so your judgment doesn't drift. If the bounce rate exceeds 2%, or the spam complaint rate approaches the 0.3% threshold recommended by major mailbox providers, open rate will be structurally suppressed no matter how much you rework subject lines. Ad CTR uses impressions as its denominator, so even 0.5% is not a bad number, and comparing it with email CTR is meaningless.
The most common mistake is making open rate the target. Adding 'Re:' or '[Urgent]' to a subject line will almost certainly lift open rate that month, but readers feel tricked, unsubscribes and spam reports climb with it, and once your domain reputation takes a hit, recovery takes months. Lists with many Apple Mail users can show open rates of 60% because of MPP, and teams that report this as a win are often stuck when asked, 'So how many inquiries did we get?' Treat open rate as a reference point for A/B comparisons, not a goal, and connect it to landing-page engagement and form conversion after the click so the numbers don't mislead you.
John KimInstructor John Kim, author of B2B Marketing Design and CEO of Nanum Consulting
Hyerang ParkSpecialist in content storytelling and AI-driven brand contentIn the late 1990s, email marketing tools began measuring opens and clicks with tracking pixels (1px images that detect opens) and link redirects, and these became standard metrics. Since Apple introduced MPP in 2021, open rate has become less reliable, and the emphasis is shifting toward clicks and conversions.
Consider a hypothetical case. Company A, which makes industrial measuring equipment (210 employees, KRW 52 billion (≈ US$38,904,700) in annual revenue), sent a monthly newsletter to 14,000 recipients. For six months, open rate held steady at 31–33%, yet contact-form visits fell from 18 a month to 6. The diagnosis began when someone in a sales meeting said, 'I haven't met a single customer this year who got in touch because of the newsletter.'
- When Manager Kim on the marketing team pulled six months of data again, the open rate was unchanged at 32%, but CTOR had been cut in half, from 11% to 5%. The problem was in the body, not the subject line.
- In a recent issue, there were 9 links, covering new products, job postings, and even a trade show announcement. The team lead pointed out, "I can't tell what the reader is supposed to click," and from the next issue the newsletter was restructured around one key piece of content and one button.
- Two subject-line options were first sent to 10% of recipients, or 1,400 people. '5 Checks Before Adopting Predictive Maintenance' got 38% and '[Company A Newsletter] December Issue' got 26%, so the winner went out in the main send.
- To filter out open counts inflated by Apple MPP, Assistant Manager Park in inside sales tracked landing-page dwell time of 30+ seconds after a click, along with form-entry counts, as separate items in the weekly report.
- After sending two re-engagement emails to 3,200 recipients who had not responded in 12 months and then removing them from the list, send volume fell, but the spam complaint rate dropped from 0.28% to 0.06%.
- Four months later, CTOR rose from 5% to 13% and CTR from 1.6% to 4.2%, and contact-form submissions went from 6 to 21 a month. Three of those moved to the quote stage and were added to the sales team's pipeline.