Click-through rate (CTR) and click-to-open rate (CTOR) were once considered must-have metrics for email marketers—but is that still the case, and what's the difference between the two?
This article is designed to give you a crisp understanding of each metric, how Apple's Mail Privacy Protection (released in 2021) has impacted their reliability, and a short list of what to look into if you start to see either one of these two numbers looking a bit low.
It’s no big deal really—it’s just your audience engagement that hangs in the balance. So, shall we begin?
Apple’s Mail Privacy Protection (MPP) and its impact on email marketing metrics
As of September 2021, Apple Mail users now have the option to opt out of tracking that allows marketers to know if, when, and how an email is opened.
To put it simply, this is a big deal because:
- Apple Mail is by far the most popular email client (~60% market share according to Litmus).
- When people are given the opportunity to opt out of data tracking, they usually take it.
Therefore, MPP has significantly reduced the reliability of open rate metrics.
As a result, you’re likely to see:
- Artificially inflated open rates (OR) because Apple now pre-loads email data regardless of whether a user actually opened an email.
- Artificially decreased click-to-open rates (CTOR) given unique clicks is divided by unique opens, which are artificially high.
What is reliable when it comes to Apple Mail tracking? Clicks and click through rates (CTR).
Mail Privacy Protection does not impact how total email clicks are tracked, making it a great metric to gauge which email is most engaging.
What’s a good click-through rate or click-to-open rate?
Every marketer loves a benchmark (Campaign Monitor’s report is a good one) but none is more valuable than a strong grasp of your own historic performance. We recommend tracking by campaign groups so that you can establish baseline performance metrics for your unique brand by email type (sales promo vs. newsletter, etc.). Then, evaluate how any individual email send compares relative to your own unique baseline.
Now, that’s an insight you can take action on.
Click-through rate vs. click-to-open rate
Why it matters
click-through rate (CTR)
- Gauges how many clicks you received relative to how many emails were delivered
- Indicates the quality of your email list
click-to-open rate (CTOR)
- Indicates how well your email content compels a reader to take action (click on a call to action button).
- Indicates the quality of your email list
What it measures
- Measures clicks as a percentage of all emails delivered
- Measures clicks as a percentage of opens
How it's calculated
- Unique Clicks / Total Delivered*
- Unique Clicks / Unique Opens
*Total delivered refers to the total number of times your email successfully made it to the inbox of a subscriber (excluding hard and soft bounces). Keep in mind this is almost always a smaller number than the total ‘sent’ emails.
Why use only unique clicks and opens?
Because total clicks and opens will count the same user opening and clicking on an email multiple times and tends to skew your data. Instead, you want to measure how many unique individuals take these actions.
Neither is a “bad” or “better” metric—it all depends on what question you most want to answer.
- How well did your subject line work? — Open Rate
- How many clicks did your emails generate? — CTR
- How well did your email perform? — CTOR
Tracking both and understanding what they represent is essential for growing an email list that consistently contributes to your company’s bottom line.
What to do if you have a low CTR or CTOR?
It’s great when you can measure something, sure—but as an email marketer, you’re always looking for signals from your data about what you should do differently.
- How is this data going to change your decision-making?
- If you make a different choice, will you have a small or large impact?
Perhaps you sent to a large list of 10,000 with a low open rate of 10%. But your email content was extremely compelling and drove the majority (75%) of readers back to your website.
Your CTR won’t reflect that reality, because 1000/10000 = 10% 😕. Therefore, it only tells (a small) part of the story: perhaps you had a bum subject line or an under-optimized send time that causes few people to open the email, masking the true effectiveness of your email content.
What to do if you have a low CTR:
Issues with hygiene
- Prune your list of inactive subscribers
Issues with deliverability (spam/firewall)
- Try staggared email sends
- Warm up a new IP or sending domain
- Evaluate your IP reputation
Issues with the relevancy of the subject line or preview text
- A/B test your subject line & automatically choose the winner
What to do if you have a low CTOR:
When you really want to understand how your email content performs against your goals, CTOR is, arguably, the best metric for measuring the effectiveness of your email campaign’s overall messaging. Unlike CTR, CTOR considers only the people who actually opened the email and answers the question: how well my email content compels a reader to take action (click)?
Issues with the relevancy of the email content
- Was it sent to the most targetted segment?
- Does the content/offer align to the audience’s interests?
- Did the first section of the email quickly address “why I should care”?
- Was the messaging clear and concise?
Misalignment with your subject line
- Does your email deliver what your subject line promised?
Issues with the call to action
- Optimize your email for a single call to action (CTA) and make it the most visually dominant
- Try an A/B test to learn whether a hyperlink or button CTA work best for your audience
- Try an A/B test to learn whether multiple CTAs increase or decrease engagement
Issues with email design
- Try split testing a plain text email vs. one that includes custom graphics
- Preview your email on multiple devices (viewports) and email clients prior to sending.
How do you calculate CTOR and CTR?
Let’s run through a few quick examples so that you’re fully comfortable with the math.
Let’s imagine your monthly company newsletter was sent to a segment of 5,000 people, but only 4,850 people actually receive your email—the rest are hard or soft bounces due to bad email addresses. That gives you a delivery rate of 97% (4850÷5000)—not bad.
Your email open rate (or CTOR) is 20%, which means 970 people will actually see the (phenomenal) content in your email (0.2 ✕ 4850).
Of those 970 people, you get 68 unique clicks which is a 7% CTR (68÷970).
Which metric is more useful - CTR or CTOR?
By now, you know it’s not a matter of one inherently being more useful than the other—CTR and CTOR give you two key indicators for how your email marketing is performing—neither one is complete on its own and CTOR has certainly been impacted by Apple's Mail Privacy Protection.
As the savvy email marketer that you are, you should be tracking both: establishing a baseline specific to your brand (and broken down by email type) then comparing every new send to this metric.