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The Top 10 Most Popular Email Clients of 2016


2016 brought significant changes for the most popular email clients, proving once again that email is still alive and kicking. This year saw the launch of a new version of iOS (iOS 10) and the Yahoo! Mail Android app dropping support for media queries. The biggest news of 2016 for email geeks? Gmail supporting <style> and media queries, effectively supporting responsive design.

This is big news for the email community not on principle, but because of the volume of opens in each of these email clients. We tracked over 13 billion opens in 2016. And while a few things stayed the same—the top three email clients have claimed those spots several years in a row now—we saw plenty of movement this year, namely:

  • iPhone, Gmail, and iPad remained the top three email clients
  • Android remained #4 but dropped more than 2% along the way
  • Yahoo! Mail dropped from #7 to #8
  • Thunderbird lost the #10 spot to Windows Mail; then Windows Live Mail and Windows Mail flip-flopped to #10 and #9, respectively

Mobile, Webmail, and Desktop Trends


While mobile remained dominant, this year did see some changes (and oscillations) for mobile, webmail, and desktop.

  • Mobile began and ended the year at 54%, though it did jump to as high as 56%.
  • Desktop began the year at 19% and dropped to 16%.
  • Webmail began the year at 27% and grew to 30%.

Mobile has dominated market share for several years now, with iPhone, iPad, and Android making up the bulk of mobile’s market share.


But the drop in desktop (and subsequent rise in webmail) appears to be driven largely by growth in Gmail opens.

Our own Justine Jordan, VP of Marketing, speculated this was the result of companies moving to cloud-based solutions, rather than upgrading older versions of Outlook, back in 2015:

“Microsoft and Google continue to invest in cloud-based email solutions, and businesses seem to be following suit—moving away from installing Outlook on employee machines and using services like Office 365 and Google Apps instead.”

While general email client open data is great for looking at trends, it’s your audience that matters. With the addition of a small tracking code to your campaigns, Litmus Email Analytics generates a report of where your subscribers open your emails. Use that data to focus your testing efforts, identify opportunities for experimentation and progressive enhancement—and ensure your emails look great in inboxes where your subscribers are opening.

Comparing the Top 10 from January 2016 to the Top 10 from December 2016

Comparing the top 10 from January 2016 to December 2016, the biggest movers are Outlook, Windows, and Thunderbird, with the bottom half of the list seeing the most changes:


While iPhone, Gmail, iPad, and Android remained the same throughout the year, Gmail has picked up some serious growth, now up to 20%. Gmail reports more than 1 billion monthly users, with 75% of them on mobile devices, as more and more users are choosing Gmail.

Most of the movement in rankings came from the bottom half of the list, with Yahoo! Mail losing a spot to, Thunderbird dropping out of the top 10, and seeing Windows Mail surpass Windows Live Mail for the #9 spot.

Gmail Drives Webmail Growth, Increases Market Share 4%

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Gmail remains the most popular webmail client by far, jumping up from 16% to 20% this year, with the most significant growth occurring in the last few months.

This is happening at an exciting time for email geeks! Though it’s been difficult to design and develop for in the past, the Gmail team rolled out support for responsive design, improved font styling, and <style> in September of 2016. Better support for CSS in Gmail means more accessible campaigns, faster turnaround times, and less bugs to troubleshoot and fix, especially for a client with so much market share.

This comes off the heels of the Gmail team rolling out support for display:none, a CSS property that can hide specific parts of an email. This adds even more support for favorite techniques, like hiding preheader text so you can control what preview text appears in the inbox without having it displayed in the body of the email, or controlling desktop-specific content to hide if the user is opening on a mobile device.

We’re following all Gmail changes closely with our live ticker as they roll out. While things are still changing, all Gmail mobile apps now support responsive email, as do G Suite accounts. Users who access Gmail web clients via a mobile browser, however, will still experience a lack of support for embedded CSS, media queries, and responsive design. The same is true for everyone who uses Gmail to access non-Gmail addresses via IMAP or POP.

If you’re looking for email-related New Year’s Resolutions, adding responsive design into your workflow is a great start (or, for those already using it, updating your templates to accommodate Gmail’s changes). Responsive design involves the use of fluid tables, images, and media queries to control the layout of email so that your message adapts to any screen size or device. While it may seem complicated, we’ve got a complete how-to guide to get you started.

Microsoft Moves


In desktop, Outlook remained fairly steady this year, dropping from 7% to 6%. For webmail, grew from 2% to 5% throughout the year.

Outlook is a notorious offender for rendering quirks, but we’re teaming up with Microsoft to make email better. We’ll help them prioritize email rendering bugs from the community and identify issues faster. We’re looking forward to sharing some bug fixes and improvements in the coming months. In the meantime, if you’d like to report an Outlook bug, shoot us an email:

Windows Mail officially overtook Windows Live Mail for the #9 spot in October 2016, and its lead continues to increase, up to 1.31% over Live Mail’s 1.07%. This trend will continue as Microsoft finishes retiring Windows Live Mail.


This data is derived from over 13 billion opens collected worldwide with Litmus Email Analytics between January 1, 2016 and December 31, 2016. It highlights worldwide trends across all industries and verticals. Some email clients may be over- or under-represented due to image blocking. Tracking trends over time is the best way to monitor open data for email!

Check out our other top 10 lists:

Kayla Voigt

Kayla Voigt

Kayla Voigt is a freelance writer