April 26, 2016

Email Research Chart: Email opens trends on mobile devices in 2015

SUMMARY: As mobile opens have surpassed desktop opens, more and more marketers are faced with the challenge of creating mobile-friendly emails. This week, we look at the email open trends of the most popular mobile device types, and how marketers can optimize for mobile in general and for iPhones, specifically.
by Dr. Liva LaMontagne , Editorial Research Manager

Email is one of the top communication methods that customers want marketers to use, and more than half of those emails are opened on mobile devices.

To create functional mobile email experiences for their audience, marketers need to understand the specific requirements for the different types of devices their customers use.

This week, we look at trends in the most popular mobile device types throughout 2015, and what marketers can do to optimize their email campaigns for mobile in general and for iPhone, specifically.


Litmus recently released a report on the state of email based on 13 billion email opens worldwide from its platform, collected January 2015 through December 2015. Of those, 7.15 billion emails (55%) were opened on mobile devices.

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Click to see a larger, printable version of the chart

According to the report, Android opens increased from 7% at the beginning of 2015 to 10% of total opens by the end of the year, and iPhone opens rose from 27% to 33% of total opens. Conversely, iPad opens declined over the course of the year.

With the iPhone being the most popular device for mobile email opens, how can marketers prepare to deliver the best customer experience through it?

Lauren Smith, Content Marketing Manager, Litmus, offered the following five points of advice on optimizing email for mobile in general, as well as specifically for the iPhone email client.

Focus your mobile optimization efforts

With dozens of smartphones and email apps on the market, each with their own rendering quirks, Smith recommended that marketers should understand where their audiences are opening their emails to narrow down which programs and apps to test in.

She added that these insights can be found in many email service providers' data sets, or via email analytics tools. This approach will save time and ensure that their emails will render well in all of the necessary environments.

After narrowing down their testing efforts, the next step Smith recommended is to understand the HTML and CSS support in those mobile email apps.

Since responsive design isn't supported everywhere, it's critical to use mobile-friendly elements, such as a single-column design as well as larger text and calls-to-action.

In addition, many mobile email apps — like the Android native email client and Windows Phone 8 — block images by default, so marketers should use HTML text and ALT text to ensure that their email is actionable.

Smith also advised marketers to streamline their content and prune any less useful or irrelevant links, copy and images. She emphasized that marketers should make sure they are using every inch of screen real estate on mobile devices to their advantage, which includes paying attention to subject lines and preview text.

Smith explained that subject lines and preview text may be truncated on a small screen. Therefore, marketers should pack the beginning of their subject lines and preview text with keywords and phrases that perform.

Moving on to optimizing email for iPhone specifically, Smith pointed out a couple of things to consider and test out.

Be aware of blue links in emails viewed on iPhones

Phone numbers, addresses, dates and sometimes seemingly random words like 'tonight' automatically turn blue and are underlined in emails viewed on an iPhone. These bits of information trigger app-driven events, such as making a call, launching a map or creating a calendar event.

While very handy in plain-text or personal emails, it can cause issues in HTML emails. Smith mentioned that blue links on a blue background can become illegible and could not fit well with the overall branding of the email.

However, Smith suggested a couple of CSS solutions to prevent auto-links from ruining marketers' designs – from Litmus and RemoveBlueLinks.com.

Use preview text strategically

Alongside the subject line and sender name, optimizing preview text (also referred to as snippet text or a preheader) is one of the most effective ways to increase open rates. Smith emphasized that all of the major iPhone email apps support preview text, including the native email app, Gmail app and Yahoo! Mail app.

Consequently, marketers can use preview text to encourage their subscribers to open by expanding on the value stated in the subject line. Smith emphasized that preview text should be useful, specific and, if appropriate, have a sense of urgency.

"Like subject lines, it's also a great place to A/B test," she added.

Smith suggested that marketers keep character count top of mind, stating the differences between different email apps – while the native email app iPhone 6 has two lines of preview text, the iPhone 6S Plus has three. Smith cautioned that text like "View in Web browser" and "Forward to a friend" should not appear in this coveted space.

Be mindful of text autoscaling on iPhone screens

Considering scaling, Smith cautioned that the native email app on iPhone has a minimum font size of 13px and will auto-adjust anything smaller than that size, often breaking navigation bars and other "tiny text". While marketers can "fix" this issue with a bit of CSS work, she advised to use caution, since the app is increasing the font size for a good reason: anything smaller than 13px would be hard to read on an iPhone screen.

Smith added that the Gmail app on iPhone will automatically enlarge fonts in some emails, sometimes by as much as 50%. While this change improves legibility for most messages, it can break the look of others. She advised that marketers can prevent automatic resizing with a little bit of code.

Not all apps that your audience members use on iPhones support responsive design

While the native iPhone email app supports media queries, the Gmail app does not. As a result, Smith suggested that marketers use mobile-friendly elements, like large text and a single-column design, for functional rendering in the Gmail app and other apps where responsive design isn't supported.

As an alternative approach, which is supported in the Gmail app, Smith suggested Hybrid email development (also referred to as spongy email development). It involves using fluid widths, rather than media queries, to adapt designs based on screen sizes.

Related resources

Subscribe to MarketingSherpa Chart of the Week — Get data and discoveries delivered to your inbox

Litmus' 2016 State of Email Report

Email Research Chart: Which industries have the highest click-to-open rates?

Email Research Chart: Which campaign types are most used and effective?

Marketing Research Chart: How consumers prefer to receive updates and promotions from brands

Marketing Research Chart: How Millennials and Baby Boomers want to receive updates and promotions

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