What is the best way to estimate US consumer email inbox market share between Gmail and Apple Mail?

Key findings

• Data discrepancies: There is a lot of conflicting data regarding email client market share, especially post-MPP, which complicates precise estimations.
• Impact of MPP: Apple Mail Privacy Protection (MPP) obfuscates user agents and pre-fetches images, making it difficult to accurately track open rates and, consequently, email client usage. This affects how accurate email client market share data is.
• Client vs. provider: It is crucial to distinguish between an email client (the application used to view emails, like Apple Mail) and an email provider (the service that hosts the inbox, like Gmail). A user with a Gmail address might read their email in the Apple Mail client, blurring statistics.
• Interactive email support: For interactive emails (e.g., AMP for email), understanding the market share of clients that support these features (Gmail, Yahoo, Apple Mail) is vital for estimating audience reach.
• AMP for email: While some senders see significant AMP engagement (e.g., 34% of consumers in one case), Yahoo's rendering of AMP emails can be inconsistent, impacting reach for interactive content.

Key considerations

• Define your objective: Determine if you need market share data for email clients (MUA) or email providers (MX) as the methodologies and interpretations differ greatly.
• Adjust for MPP: When assessing open rates for market share insights, acknowledge the skew caused by Apple Mail Privacy Protection. Consider how accurate email open rates are with this feature.
• Look beyond raw numbers: Anecdotal evidence suggests that users often access Gmail accounts through Apple Mail clients, complicating simple client-based statistics. For broader market insights, consider aggregated email marketing statistics.
• Focus on interactive compatibility: If your goal is to estimate reach for interactive emails, identify which clients and providers (like Gmail and Apple Mail, with its specific rendering layer) support these features.
• Provider-level metrics: For a more reliable view of where emails are delivered, focus on mailbox provider data (MX) rather than relying solely on client-side tracking, as explained in articles about average email deliverability rates.

Key opinions

• Open rate unreliability: Some marketers express skepticism about the reliability of market share data derived from image-based tracking due to caching and proxy issues, particularly after MPP.
• Litmus data criticism: While Litmus is often cited, some marketers find its data on email client usage to be inaccurate, implying that a more refined approach is needed when looking at how accurate email client market share data is.
• Gmail through Apple Mail: Many marketers observe that a considerable number of their contacts access Gmail accounts via Apple Mail clients, complicating the distinction between provider and client usage.
• Interactive email reach: There's a strong interest in determining the total percentage of users who can experience interactive email content, including those using Gmail, Yahoo, or Apple Mail.
• AMP adoption: Some marketers find that Yahoo rarely renders AMP emails, despite having domains approved, indicating potential issues with the approval process or rendering consistency.

Key considerations

• Methodology questions: Marketers frequently question the best methodology for tracking email client usage accurately, especially given the limitations of traditional pixel-based tracking.
• User agent obfuscation: The challenge of obfuscated user agents due to proxies and caches makes reliable MUA market share tracking difficult for marketers. Consider how email analytics platforms classify client usage.
• Focus on interactive content: When planning interactive email campaigns, marketers should estimate the potential reach by considering the combined market share of supporting clients, such as Gmail and Apple Mail.
• AMP approval process: If utilizing AMP for email, marketers should investigate Yahoo's AMP approval and rendering processes for their domains, potentially contacting Yahoo support for clarification.
• Overall inbox placement: Understanding market share helps marketers deduce inbox placement metrics and manage their strategies effectively.

Key opinions

• MUA vs. MX confusion: It's essential to clarify whether the market share refers to Mail User Agents (MUA, the application displaying the message) or Mail Exchange (MX, the email provider), as these are distinct metrics.
• Unreliable image tracking: Experts assert that relying on images to track MUA market share is fundamentally flawed due to various caches, proxies, and user agent obfuscation, making most published statistics inaccurate. This affects how to estimate real open rates.
• The X inbox problem: An email can be in a 'Google Inbox' but be read in 'Apple Mail' or even the Yahoo Mail app, making it difficult to pinpoint the exact viewing application.
• Ballpark estimates only: Given the complexities, reliable, precise numbers are unlikely; only ballpark figures based on broad sending experience can be provided.
• Yahoo AMP support: Experts confirm that senders can contact Yahoo's support for AMP for email approval inquiries, suggesting direct communication is the best approach for issues.

Key considerations

• Clarify metric needs: Before seeking data, define whether you need to understand email client usage for engagement metrics or email provider delivery for deliverability metrics.
• Avoid flawed tracking: Do not rely on traditional image-pixel-based tracking for accurate email client market share due to its inherent unreliability, especially for Apple Mail Privacy Protection (MPP) and its effect on Apple Mail's intentional opens.
• Consider the user journey: Acknowledge that users can receive email in one provider's inbox (e.g., Gmail) but view it through another client (e.g., Apple Mail), which impacts interactive content rendering.
• Strategic AMP deployment: For Yahoo AMP issues, direct communication with their support is recommended to resolve rendering or approval challenges.
• Focus on deliverability: While client usage is tricky, focusing on overall deliverability to major mailbox providers is more actionable. Explore ways to measure email deliverability.

Key findings

• MPP's design: Apple Mail Privacy Protection (MPP) is designed to protect user privacy by pre-loading email content, including tracking pixels, regardless of whether the user opens the email. This renders traditional open rate metrics inaccurate for true engagement.
• User agent limitations: User agent strings, traditionally used to identify email clients, are increasingly being masked or generalized by privacy features and web proxies, limiting their utility for market share analysis.
• Focus on engagement: Documentation often redirects attention from open rates to more reliable engagement metrics like clicks, conversions, or website activity to assess campaign performance.
• AMP email guidelines: Official guidelines for AMP for email (from Google and Yahoo) specify technical requirements for implementation and approval, indicating that not all domains will have automatic support for interactive content.

Key considerations

• Review privacy updates: Stay informed on privacy updates from major email providers like Apple and Google, as these directly impact how email engagement can be measured. This includes understanding Apple's new inbox tabs and their effects.
• Adapt tracking strategies: Adjust your email analytics to de-emphasize open rates for client market share and instead focus on alternative metrics that reflect true user interaction.
• Understand AMP requirements: For interactive AMP emails, ensure your domains meet all sender requirements and follow up with providers if rendering issues persist.
• ISP-specific data: Leverage tools like Google Postmaster Tools to gain insights into your sending reputation and deliverability specifically with Gmail, as this data is more reliable than client-side market share estimates.