Email Client Market Share & Apple MPP Statistics [2023 Update]

Mike Arsenault
February 2, 2023
minute read

In 2023, it is projected that 347.3 billion emails will be sent and received worldwide on a daily basis. That number is projected to increase in 2024 to 361.6 billion per day.

Rejoiner, as an email service provider, represents a small percentage of that overall volume. But, due to commonalities of our customer base (98% DTC ecommerce businesses in the United States) our email client market share data offers some interesting insights around the preferred email clients of consumers who shop DTC in North America.

It should be noted that any email service provider’s ability to accurately track email clients changed significantly in September 2021 as a result of Apple’s launch of Mail Privacy Protection

Here’s how:

Our ability to track email client usage relies on an invisible pixel that loads when an email is opened. That pixel makes a request to our web servers, returning data about the recipient’s user agent.

Apple MPP obfuscates this and any data that would provide the location, device type, system settings, browser, or email client of a recipient. This data, historically returned as part of the user agent string, is absent from any request received from an Apple MPP open. 

Although we lost the ability to truly measure email client market share with this development, the proliferation of MPP over the last 18 months is worth observing.

Let’s get into the data. 

What is email client market share?

An email client is desktop or cloud-based software that people use to manage, organize, read and send email. The most popular email clients are Gmail (Google), Outlook (Microsoft), Apple Mail (Apple) & Yahoo Mail (Yahoo).

Our methodology

We analyzed two datasets for this research:

  1. We sampled 78M email opens across our customer base from 2022 to determine which email clients were the most popular. We then compared our market share numbers to the December 2022 dataset from Litmus. Litmus analyzes a substantial dataset of 1.6B email opens per month across its user base. 
  2. We also sampled 100M Apple MPP email opens from 2021-2022 and measured the overall acceleration of MPP opens as a percentage of our total open volume by month. This analysis demonstrates how quickly MPP changed the landscape of open tracking.

Let’s start with the market share data:

Email client market share stats

Some notable data points:

  • In the Rejoiner dataset, Apple MPP opens represent over 70% of 2022 total opens. This is roughly 6 percentage points higher than Litmus, which makes sense given our recipients skew heavily towards consumers. 
  • The variance for Gmail is also notable. Our hypothesis here is that a higher percentage of the consumers in our dataset are in fact Gmail users, but use Apple Mail to conume most of their email.
  • The Apple data also includes a small percentage of iPhone/iPad opens that are not obfuscated by MPP. This is most likely due to a small number of users running older versions of iOS.

Apple Mail Privacy Protection stats

Perhaps the more interesting dataset demonstrates how quickly Apple MPP proliferated from the point it launched in September 2021. We started seeing MPP opens trickle in as early as April 2021, while Apple was testing this new feature set. 

By October of 2021, Apple MPP represented 19% of total opens.

As of December of 2022, Apple MPP represents over 72% of total opens. 

It is safe to say that Apple MPP has permanently altered the landscape. Email marketers can no longer rely on open rate data as an effective measure of email marketing performance, or engagement. And we must adapt to the new reality.

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Frequently Asked Questions

What is email client market share?

An email client is desktop or cloud-based software that people use to manage, organize, read and send email. Email client market share refers to measurable usage trends for each client.

What is the most used email client?

The most popular email clients are Gmail (Google), Outlook (Microsoft), Apple Mail (Apple) & Yahoo Mail (Yahoo).

What is Apple Mail Privacy Protection?

Apple Mail Privacy Protection, or MPP, refers to a set of Apple privacy features that are designed to anonymize and/or obfuscate the datasets collected by marketers from email.


Mike Arsenault

Founder & CEO

For the last 10 years, Mike has worked with brands like Moosejaw, Hydroflask, Peak Design, Triumph, Hearst & Guthy Renker to provide the strategy & technology with which they use email to drive revenue growth. He's also the Founder of Rejoiner, a SaaS marketing platform built for ecommerce businesses.

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