The Science of Email Clicks: The Impact of Responsive Design & Inbox Testing

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Whether it’s reading a blog post with your phone, catching up on Twitter with a tablet, or even previewing emails on your watch, the number and types of devices we use to consume content are growing rapidly. In fact, at least 43% of emails are opened on a tablet or smartphone. How does small-screen reading impact subscriber behavior after emails are opened?

MailChimp analyzed over 395 million emails during a 6-month period to examine how a user’s preferred device affects email engagement, investigate the impact of responsive design, and find out if testing your emails can increase click rates.


Where are subscribers clicking?

MailChimp looked at email addresses that they send to and, for every email address, the device that made the most clicks was identified as that user’s preferred device.

Desktop users click more than mobile and tablet users combined for email.

While unique click rates for desktop and tablet users are virtually the same—hovering around 3.8%—desktop users have the highest total click rate across all environments. Desktop users are not only more likely to click on an email, but those that do tend to click on numerous links. And, recipients who use mobile phones have unique and total click rates of 2.7% and 3.9%, respectively—much lower than desktop or tablet users.

Desktop and tablet unique click rates are 40% higher than mobile click rates for email.

Clicks can be considered a positive endorsement for the usability and utility of an email. Roughly half of all emails are opened on smartphones and tablets, but only 36% of smartphone and tablet users “vote” with their clicks to indicate a preference for engaging on these devices.

Improving click rates across devices

With more opens and fewer clicks happening on mobile, email designers and marketers may be rightfully concerned. How can we improve click rates across the board?

The impact of responsive design
Responsive design can provide a tailored viewing experience based on the screen size of the user’s device. Optimizing email messages to be readable on screens big and small pays off—customers using MailChimp’s responsive email templates have enjoyed higher click rates across all devices.

Unsurprisingly, responsive emails are particularly effective on mobile users. MailChimp found that unique clicks amongst mobile users for responsive campaigns rose from 2.7% to 3.1%—a nearly 15% increase. Responsive design also resulted in an increase in total clicks across desktop, tablet, and mobile.

Responsive email design results in a 15% increase in unique clicks for mobile users.

You can’t predict where subscribers will open their email. Even those that prefer mobile may open in desktop from time to time. Be sure to optimize your email so it looks great in every inbox.

The impact of inbox testing with Litmus
MailChimp’s stats back up the notion that a well-designed campaign that adapts from device to device can increase click rates. Previewing emails across an array of inboxes with MailChimp’s Inbox Inspection tool—powered by Litmus—also improves click rates. While responsive email design increased clicks 5–15%, using Litmus inbox testing increased clicks by 13–24%.

Litmus inbox testing results in a dramatic increase in unique clicks across all environments: +13% on desktop, +24% on tablets and +19% on mobile.

Which links are subscribers clicking?

Although a campaign might have a total click rate of 4–6%, these clicks are not always evenly distributed. In order to determine where subscribers are clicking, MailChimp separated the first ten links in an email by the order they appeared in an email and calculated click rates for each.

Any single click in a campaign had a click rate between 0.25% and 1.5%. Desktop and tablet users have higher click rates throughout an email, but deeper links have worse click rates across all devices. The fifth link in a campaign has roughly half as many clicks as the first link.

Does responsive design impact clicks?
Campaigns that used responsive design have higher click rates in general. However, the impact isn’t evenly spread throughout the links. MailChimp found that the first three links in an email typically saw the biggest benefit from the use of responsive design.

Unsurprisingly, responsive emails had the biggest impact on mobile click rates.

The first link in responsive emails on mobile have a 30% higher click rate than non-responsive emails.

Does Litmus inbox testing impact clicks?
Testing with Litmus resulted in a more evenly distributed click rate throughout an email. While click rates for the first links in the email decreased, this was offset by a significantly higher click rates on links located deeper in the email.

Click rates for the tenth link in Litmus-tested emails were roughly double those of their non-tested counterparts and comparable to click rates for the fifth link in non-tested campaigns.

Litmus inbox testing results in more evenly distributed clickrates throughout an email.

Optimize for your audience

As subscribers become even more mobile (hello, Android Wear, Apple Watch, and Google Glass!), it’s crucial to understand how design impacts engagement. Utilizing responsive email will allow content to scale to fit your readers’ screens, while Litmus testing ensures you deliver a clickable experience with a preview of how your emails look across devices.

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Data in this infographic is based on findings from MailChimp. A sample of 395+ million email opens in 2014 formed the basis of the analysis. Some statistics may be over- or under-represented due to image blocking. Check out the full report!