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Email Client Market Share in December 2021: Is MPP Adoption Slowing Down?


New year, same us—we’re back! It’s time for our monthly recap of email client market share where we look back at what shifts took place for the previous.

What happened in December 2021? Let’s take a closer look.

Top email clients

Before we begin, we’d like to recall that a few months ago, we introduced a new grouping for Apple clients that nests Apple iPhone (iOS Mail), Apple Mail (macOS Mail), Apple iPad (iPadOS Mail), and Apple Mail Privacy Protection (MPP-impacted opens) under the category “Apple”. To learn why, check out this blog post.

And—as we always like to note—there are two things we’d like to point out: 1) MPP hides device data so we can’t differentiate between iOS, iPadOS, or macOS, and 2) the new OSes also don’t differentiate between MPP and non-MPP in the user agent data it passes.

That said, the top 3 email clients for December 2021 are Apple, Gmail, and Outlook.

Top 10 opens

  1. Apple: 57.4%
  2. Gmail: 30.4%
  3. Outlook: 4.1%
  4. Yahoo Mail: 2.5%
  5. Google Android: 2.0%
  6. 1.0%
  7. Samsung Mail: 0.4%
  8. Windows Live Mail: 0.1%
  9. 0.04%
  10. GMX: 0.04%

Apple’s overall market share went up over three percentage points, from 54.2% to 57.4%. As a result, the rest of the email clients are seeing a slight decrease. Gmail dropped from 31.6% to 30.4%, and Outlook from 4.7% to 4.1%.

Let’s take a closer look at what’s happening with Apple:

  1. Apple Mail Privacy Protection: 41.0%
  2. Apple iPhone (iOS Mail): 10.7%
  3. Apple Mail (macOS Mail): 5.0%
  4. Apple iPad (iPadOS Mail): 0.6%

Apple Mail Privacy Protection’s share continues to climb, which isn’t a surprise as Apple’s Mail Privacy Protection (MPP) adoption increases. In October, Apple Mail Privacy Protection was at 14.4%, and in November 2021 it grew to 26.2%—a near 82% increase. As for December, Apple Mail Privacy Protection’s share was 41%—nearly a 57% increase from the previous month. As the growth from month-to-month slows down a bit, we’re wondering: Could MPP adoption be normalizing?

As a result, Apple iPhone (iOS Mail) decreased its share from 20.51% to 10.72%, as did Apple Mail (macOS Mail) from 6.79% to 4.96% and Apple iPad (iPadOS Mail) from 0.74% to 0.64%.

Want more data and trends? Check out our new and improved email client market share site, which includes Apple’s Mail Privacy Protection (MPP) data, pre- and post-MPP launch.

Opens by environment

Although MPP launched in September 2021, the data we’re able to see on MPP with Litmus Email Analytics is considered early data. December 2021 marks the fourth month we’ve been tracking MPP stats.

Opens by environment

  1. Apple Mail Privacy Protection: 40.6%
  2. Webmail: 35.6%
  3. Mobile: 13.7%
  4. Desktop: 9.1%
  5. Other: 1%

Apple Mail Privacy Protection has now taken the top spot for reading environment, surpassing webmail which was traditionally in the lead. As we mentioned earlier, MPP adoption will continue to increase as time passes.

We watched this closely over the past few months. To recap what happened: from September to October, Apple Mail Privacy Protection’s share grew from 6.6% to 14.2% (a 115% increase). Then from October to November, we also saw a smaller jump, from 14.2% to 25.9% (an 82% increase). From November to December, we saw an increase too, though less significant—from 25.9% to 40.6% (a 57% increase). Month-to-month growth appears to be slowing down here too when we look at opens by environment, a trend we pointed out earlier when looking at Apple clients.

Most popular mobile opens

When looking at mobile opens, the top 3 remain the same, as it has for months prior.

Most popular mobile opens

  1. Apple iPhone (iOS Mail): 77.6%
  2. Google Android: 14.5%
  3. Apple iPad (iPadOS Mail): 4.6%

In December, we’re seeing similar shifts to what we saw in November. Apple saw a small decrease (from 85.5% to 77.6%), while Google Android and Apple iPad saw some growth, from 9.3% to 14.5% and 3.1% to 4.6%, respectively.

Most popular webmail opens

What about webmail? The top 3 webmail clients are still Gmail, Yahoo Mail, and

most popular webmail opens

  1. Gmail: 89.6%
  2. Yahoo Mail: 7.2%
  3. 2.9%

Similar to last month, not much has happened aside from Gmail increasing slightly, from 89.2% to 89.6%. Yahoo Mail fell a small amount, from 7.4% to 7.2%, while also dropped, from 3.2% to 2.9%.

Wondering why we categorize Gmail as webmail? Learn how Gmail opens are reported in Email Analytics.

Most popular desktop opens

The same story goes for desktop: the top 3 remain the same, with Apple Mail (macOS Mail) at the top, followed by Outlook in second, and Windows live mail in third.

Most popular desktop opens

  1. Apple Mail (macOS Mail): 54%
  2. Outlook: 44.7%
  3. Windows Live Mail: 1.1%

We’re continuing to see a decrease with Apple Mail (macOS Mail), in line with the decrease we saw when looking at each Apple email client. As for Outlook, its share grew from 40.4% to 44.7%. Windows Live Mail has been growing slowly but steadily by 0.1% over the past few months, but in December, it grew by 0.2 percentage points.

Light Mode vs. Dark Mode opens

Dark Mode usage became available for us to track a few months ago, starting in September 2021. Something we’d like to note: Our Dark Mode data is based only on the Apple Mail app for iOS 13, macOS 13, iOS 14, macOS 14, iPadOS 14, iOS 15, iPadOS 15, and Apple Mail privacy-impacted devices.

Light vs dark mode

  1. Light Mode: 74.3%
  2. Dark Mode: 25.7%

Light Mode continues to reign as the popular setting, with 74.3% of all emails being opened in a light mode setting in December 2021. Over the course of our tracking, its usage has fluctuated within a small range, anywhere from 73% to 75%. For example, Light Mode was 73.7% in September, 74.4% in October, and 73.1% in November. In December, it’s back up at 74.3%, with Dark Mode at 25.7%.

Get to know your audience

While email client market share provides powerful insights about the industry as a whole, the true value lies with your audience. Get to know your subscribers, and use email client market share as a supplementary tool in your arsenal.

Over time, small shifts lead to big changes. Stay tuned next month as we share our findings and continue to track the impact of MPP.

Where did we get all this data? Our email client market share stats are pulled from over a billion email opens, anonymously collected and aggregated with Litmus Email Analytics from November 1-30, 2021. It highlights global trends across all industries and verticals. Some email clients may be over- or under-represented, particularly with mobile and webmail. This is due to image blocking or image caching, most notably with Gmail. Still curious? Learn how we get this data.


Get insights into your audience—with Litmus Email Analytics

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