2018 Email Client Market Share Trends From 11+ Billion Opens


The results are in! I've analyzed over 11 billion email opens from 2018 to break down the latest email client market share trends you need to know. Here's how the top 10 for the year shook out:

Top 10 Email Clients (Dec. 2018)

(Comparing growth from Dec. 2017)


Apple iPhone


▲ 1%




▲ 1%


Apple iPad


▼ 2%




▲ 2%


Apple Mail


▲ 1%


Yahoo! Mail (+ AOL Mail)


▲ 4%


Samsung Mail


▼ 2%




▼ 2%


Google Android


▼ 1%


Windows Live Mail



Top 10 Email Clients' Trends in 2018

The Key Trends to Know

👑 Apple and Gmail remain dominant. Combined, Apple and Gmail hold 4 of the top 5 email clients with 75% of the total market share. This is the most top heavy the email client market share has ever been. In fact, since recording email opens from 2013, this is the first time that *only* 2 email clients have had double digit (10%+) market share. Every previous year has had at least 3 clients with double digits. There's no sign of Apple or Gmail relinquishing their market share any time soon.

📉 Tablet usage continues to decline. Apple iPad usage dropped 1.42% total market share in 2018 and has lost 3% market share since the beginning of 2017. Mobile devices are consistently being used more than tablets for email opens now.

😱 Outlook (Windows) is back on the rise. Bad news, email geeks. The Microsoft Word rendering engine has actually gained 1.84% market share this year (and actually peaked as high as 2.92% growth in October 2018). It surpassed Apple Mail as the #4 email client. Conversely, Outlook.com is on the decline, having dropped 1.73% total market share this year.

❗️ Yahoo! Mail and AOL Mail's spike is due to infrastructure changes. On paper, the largest market share leap this year was Yahoo! Mail with a 4% total market share increase and a jump from #9 to the #6 spot. However, this is misleading. In March 2018, Yahoo! Mail started caching images which impacted reporting. In July 2018, AOL Mail and Yahoo! Mail merged infrastructures, which 1) caused inaccuracies in reporting for July and August 2018 and 2) makes opens from these two clients indistinguishable and these opens are now registered as one client. To me, this is now just a more accurate representation of *total* opens from both clients than existed previously.

Environment Trends in 2018

📊 Desktop opens increase (+3%) and webmail opens increase (+2%), while mobile opens remain largely static. The increase in desktop opens can be attributed to Outlook (Windows) rise while the webmail increase can be attributed to Yahoo! Mail and AOL Mail's infrastructure changes resetting its baseline.

Environment Breakdown (Dec. 2018)

Gmail caches its images, which restricts the ability to accurately distinguish between whether an email was opened in Gmail webmail vs. Gmail apps. But, if you adjust the environment metrics based on Gmail's own report that 75% of its users are mobile, here's what the trends look like:

Environment Trends (Adjusted to 75% Gmail Mobile Opens) in 2018

Environment Breakdown (Adjusted to 75% Gmail Mobile Opens - Dec. 2018)

IMO, the two Gmail-adjusted charts above are a much more accurate and likely representation of the environment breakdown today.

Rendering Engine Trends in 2018

Rendering Engine Market Share (Dec. 2018)

😭 WebKit continues its decline as it has dropped 8% since 2016. This is the most devastating trend currently, as the WebKit rendering engine is what makes progressive enhancement in email possible. Luckily, it still remains the largest rendering engine by a large margin (20%).

🙈 This is the highest market share the Microsoft Word rendering engine has had since 2015. Yikes. The good news? It's not a massive spike. It still remains 20% behind Gmail and 40% behind WebKit. (Plz stay that way k thx 🙏)

Responsive Email Support in 2018

📱 Responsive email support increases slightly to 83%. This comes at a small total increase of 1.15% from December 2017. But, the average for responsive email support all year was much lower at 80%—support spiked at the end of 2018 with an increase in mobile opens—and is still down 3% from the end of 2016 where support was at 86%. Once Outlook.com officially adds media query support this year, responsive email support will jump back to 85%.

Interactive Email Support in 2018

🔘 Interactive email support is down 8% in total since 2016. The 2% drop this past year is a direct result of Samsung Mail's total market share decrease, as Apple's overall market share remained static. The overall downward trend of interactive email support the past couple of years is a direct correlation to WebKit's decrease in market share. Note: Interactive email as defined by these metrics is support for <input> elements and the :checked pseudo-selector. Otherwise, you can argue that interactive email support will jump to 77% once Gmail releases ⚡️AMP4Email.


Everyone has a different audience. Your subscriber data may (and probably does) vary vastly from these global metrics reported. It's best to use a service like Litmus or Email on Acid to see which email clients use to subscribers open your emails.

All email opens data provided by emailclientmarketshare.com.

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