Why is it difficult to get accurate email client market share data?

Email client market share data, especially post- Apple Mail Privacy Protection (MPP), is less reliable because MPP pre-fetches images, making it appear as if an email has been opened even if the user hasn't seen it. This inflates open rates for Apple Mail , distorting overall statistics. Different sources use different methodologies, leading to varied results.

What metrics should I focus on instead of open rates?

Instead of open rates, focus on engagement metrics like click-through rates, conversions, and direct replies. These actions require explicit user interaction and are not affected by privacy features like MPP. For interactive content like AMP for Email or Apple Mail -specific layers, track interactions within those components to get clearer data on inbox placement .

What are the current ballpark market share estimates for Gmail and Apple Mail in the US?

While exact numbers vary, general estimates for US consumer email client market share suggest Apple Mail (across iOS and macOS ) holds approximately 45-55% of opens, and Gmail (web and mobile apps) holds around 30-40%. These are informed estimates, not definitive figures.

How can I estimate the reach of interactive emails?

When sending interactive emails (e.g., with AMP for Email or Apple Mail -specific layers), use your internal analytics to track direct interactions like clicks or form submissions. For Gmail AMP, these are clear indicators. For Apple Mail , observe the rendering of conditional HTML or CSS specific to the client, combined with device usage data. This helps you deduce the reach of your interactive content.

What is the best way to estimate US consumer email inbox market share between Gmail and Apple Mail? - Technical - Email deliverability - Knowledge base

Estimating the precise market share of email inboxes, particularly for US consumers between

Gmail and

Apple Mail, is a complex task. The data available often appears contradictory due to different methodologies and the evolving landscape of email privacy. Traditional metrics, like open rates, have become less reliable, especially since the introduction of Apple Mail Privacy Protection (MPP).

Our goal is to understand not just which email provider holds a message, but which specific application a consumer uses to interact with that message. This distinction is crucial for marketers designing interactive email experiences, such as those using AMP for Email or Apple Mail-specific rendering layers.

While perfect accuracy might be elusive, we can still develop a robust estimation methodology. This involves understanding the nuances of how email clients and providers operate, interpreting available data with a critical eye, and focusing on engagement metrics beyond simple opens.

The challenge of accurate measurement

The primary challenge in estimating email inbox (or client) market share lies in how engagement is measured. Historically, marketers relied heavily on the open rate, which is typically tracked via a tiny, invisible pixel image loaded when an email is viewed. However, changes like Apple Mail Privacy Protection (MPP) have fundamentally altered this.

MPP, introduced with

Apple iOS 15, pre-fetches and caches all images in emails sent to

Apple Mail users, regardless of whether the user actually opens the email. This results in inflated open rates for Apple Mail, making it difficult to distinguish between a true open and a pre-fetch. This greatly impacts the accuracy of email client market share data.

Understanding MPP's impact

Apple Mail Privacy Protection (MPP) fundamentally changed how email opens are tracked. By routing all email images through a privacy-focused proxy,

Apple obscures the actual open behavior of users. This means that an email's open pixel may fire even if the user never saw the email, making open rates unreliable for

Apple Mail users.

It's also essential to distinguish between an email client (Mail User Agent or MUA) and an email provider (Mail Exchange or MX). An email provider, like

Gmail or

Yahoo Mail, is where the email account is hosted. An email client, like

Apple Mail

or Outlook, is the application used to view emails. A user with a

Gmail address might still read their emails in

Apple Mail, complicating client-specific market share estimates.

Many industry reports attempt to provide email client market share data. Companies like

Litmus are often cited, with

Apple Mail consistently showing a dominant market share (often over 50%), while

Gmail typically holds around 30% to 35%, according to various industry reports. However, these figures are largely based on open rate data, which, as discussed, is now significantly skewed by MPP.

The discrepancies arise because different data providers use different methods to collect their statistics. Some rely on user-agent strings, which can be obfuscated or inconsistent, while others aggregate data from their own customer bases, which may not be representative of the broader US consumer market. This means any single reported market share percentage should be viewed with caution.

Source	Apple Mail Share	Gmail Share	Caveat
Litmus	50-60%	30-35%	Inflated by MPP, based on open rates.
EmailToolTester	55.64%	31.16%	Globally sourced data, may not reflect US specifically.
TechJury	51.52%	26.72%	Based on email opens, impacted by MPP.

For US consumers, a reasonable ballpark based on aggregated data and informed experience suggests that

Apple Mail (across

iOS and

macOS) likely accounts for approximately 45-55% of email opens, while

Gmail (across webmail and its mobile apps) holds around 30-40%. Other clients make up the remaining percentage. Remember, these are estimates, and precise numbers are challenging to pinpoint due to the factors mentioned earlier.

Beyond open rates: tracking engagement

Given the unreliability of open rates, particularly for

Apple Mail users, marketers should shift their focus to more reliable engagement metrics. These include clicks, conversions, and direct replies. These actions require explicit user interaction and are not subject to pre-fetching by privacy features.

When dealing with interactive emails, like those using

AMP for Email or custom

Apple Mail layers, tracking becomes more nuanced.

Gmail users who interact with AMP components are explicitly engaging with your content, and this can be tracked. Similarly, the rendering of a specific

Apple Mail-specific HTML layer can indicate an

Apple Mail user, regardless of open pixel behavior. This requires a different approach to deducing inbox placement metrics.

AMP for email

AMP for Email allows senders to include dynamic, interactive content within their emails. Supported primarily by

Gmail and a few other providers, this content can include forms, carousels, and live updates.

Tracking: Interactions within AMP components are measurable. If a user submits a form or clicks a dynamic element, this provides clear engagement data.
Deliverability: Requires a fallback HTML version for clients that don't support AMP. Ensuring good deliverability for both versions is key.

Apple Mail-specific layers

Using CSS and HTML, marketers can create conditional content that only renders when an email is opened in the

Apple Mail application. This provides a way to deliver interactive experiences to

Apple users without relying on AMP.

Tracking: While not as direct as AMP, the rendering of these specific layers can, with careful setup, provide a proxy for Apple Mail usage. It still requires some inference due to MPP.
Adaptation: This method requires precise coding to ensure compatibility and avoid rendering issues in other clients. Understanding how Apple Mail processes HTML is essential.

Ultimately, the most accurate way to gauge your specific audience's email client usage is through first-party data. Analyze click-through rates, conversion data, and any explicit interactions with your emails that are not reliant on open pixels. This allows for a more realistic understanding of how your subscribers engage, providing better insights for email deliverability metrics.

Practical estimation for interactive content

To estimate the total percentage of US consumers who can see an interactive email (either via

Gmail AMP or

Apple Mail-specific layers), you'll combine your own analytics with the best available market share estimates. For

Gmail, direct AMP interaction rates are fairly accurate. For

Apple Mail, it's more about inferring usage based on the rendering of specific HTML content that only

Apple Mail supports, combined with observed engagement patterns from those users.

If your internal data indicates that, for example, 34% of your consumers engage with AMP, you can consider that a solid baseline for

Gmail-like interactive emails. For

Apple Mail, you might estimate a percentage based on devices. If 50% of your audience uses

Apple devices, a significant portion of those will likely interact with your

Apple Mail-specific layers. Summing these percentages gives you a practical ballpark estimate.

Basic Apple Mail specific CSS examplecss

/* Example CSS for Apple Mail specific content */
@media only screen and (min-device-width: 320px) and (max-device-width: 667px) {
  div[id^="applemail_interactive"] {
    display: block !important;
  }
}
/* In your HTML */
<div id="applemail_interactive" style="display:none;">
  <!-- Apple Mail specific interactive content -->
</div>

For

Yahoo Mail, while it is an AMP-supporting provider, their rendering of AMP emails may be less consistent than

Gmail. If you're experiencing issues with AMP rendering on

Yahoo, especially after applying for domain approval, it's recommended to reach out to their support for assistance. They have specific guidelines and approval processes for AMP senders.

For specific assistance with

AMP for Email approvals, especially if you have multiple domains, you can reach out directly to Yahoo's sender support.

Views from the trenches

Best practices

Focus on engagement metrics beyond opens, such as clicks, conversions, and replies.

Use first-party analytics from your email service provider to understand your audience.

Segment your audience based on known client usage or device types for better targeting.

Test your interactive email content thoroughly across different clients.

Common pitfalls

Over-relying on published market share data without considering MPP's impact.

Assuming open rates are accurate indicators of active engagement for all clients.

Neglecting fallback content for interactive emails in unsupported clients.

Not distinguishing between email client and email provider data.

Expert tips

Consider a shift towards user surveys or preference centers to directly ask subscribers about their preferred email client or device, providing invaluable first-party data.

Implement unique click tracking URLs for different email client rendering paths (e.g., Apple Mail-specific links) to measure engagement within those environments more accurately.

Analyze device usage data from your website or app analytics to infer the likelihood of users checking emails on iOS devices, which often correlates with Apple Mail usage.

Monitor your DMARC reports to understand delivery trends, as these can provide insights into which mailbox providers are accepting your mail, even if specific client usage is opaque.

Expert view

Expert from Email Geeks says that reliably tracking Mail User Agent (MUA) market share using images is difficult due to various caches and proxies that obfuscate user agents, making numerous well-known statistics mostly inaccurate.

April 20, 2024 - Email Geeks

Marketer view

Marketer from Email Geeks says that many friends and clients access Gmail emails using Apple clients, anecdotally suggesting a significant crossover in usage patterns.

April 21, 2024 - Email Geeks

Navigating the evolving inbox landscape

While obtaining a perfectly accurate US consumer email inbox market share between

Gmail and

Apple Mail remains challenging due to privacy changes like MPP, marketers can still develop reliable estimates. This involves understanding the distinction between email clients and providers, interpreting third-party data critically, and prioritizing verifiable engagement metrics over traditional open rates.

By leveraging your own first-party data, focusing on clicks and conversions, and strategically designing interactive emails with fallback content, you can gain a practical understanding of your audience's preferences and ensure your messages reach their intended application. The landscape continues to evolve, making continuous learning and adaptation key to effective email deliverability.