What are the lists of subdomains for major email providers like Google, Microsoft, Yahoo, and Apple?

Key findings

• No exhaustive list: A comprehensive, static list of all subdomains for major email providers is generally not available, as they dynamically manage hundreds of consumer domains and thousands of business domains.
• Primary domains: Each provider has widely recognized primary domains such as gmail.com, outlook.com, yahoo.com, and icloud.com, along with numerous historical and associated subdomains (e.g., hotmail.com, ymail.com, me.com).
• Segmentation value: Knowledge of these domains is highly beneficial for segmenting email databases, tailoring content, and understanding audience distribution across different providers, which impacts deliverability. For more on this, explore why to use email subdomains for deliverability.
• Market share insights: While Gmail often holds the largest share, the relative percentages of Microsoft and Yahoo domains can fluctuate, with some senders observing higher Yahoo volumes.
• Apple's emergence: Apple's email presence, including iCloud Mail and Private Relay, is growing in significance, making it a key player alongside the traditional 'MAGY' (Microsoft, AOL, Gmail, Yahoo) grouping.

Key considerations

• Dynamic nature: Any static list will quickly become outdated. Continuous monitoring and adaptation are necessary.
• MX record lookups: For the most accurate identification, checking the MX (Mail Exchange) records of domains can confirm which email provider hosts them. This approach helps identify mail-hosted domains across major providers.
• New sender requirements: Recent policy updates from Google, Yahoo, and Microsoft apply to all their hosted domains, emphasizing the need for strong authentication and low spam rates. Consult our guide on complying with Outlook's new sender requirements.
• Privacy concerns: Compiling and sharing extensive lists of domains may inadvertently raise privacy questions, particularly when tying domains to specific user bases.

Key opinions

• Database analysis: Identifying these subdomains is essential for dissecting database composition and understanding the percentage of subscribers on each major provider. This data enables more informed marketing decisions.
• Targeted strategies: Segmenting audiences by mailbox provider allows for customized sending strategies, which can improve engagement and optimize campaign performance. Learn more about main domain names used by large free email providers.
• Market share shifts: Marketers observe dynamic shifts in subscriber volume, noting instances where Yahoo's percentage on their lists has surpassed Microsoft's, indicating evolving user preferences.
• Legacy domain awareness: Even older domains like AOL, while less prominent, still exist within the ecosystem and are often grouped under their current parent companies (e.g., Yahoo/Oath).

Key considerations

• List completeness: Static lists are inherently incomplete; they provide a snapshot rather than real-time comprehensive data due to the constant creation and consolidation of domains.
• Impact on strategy: Variations in subscriber distribution across providers necessitate flexible email strategies, especially concerning content, sending frequency, and overall deliverability practices. Read about email deliverability issues.
• Audience demographics: The demographic makeup of audiences using different email providers can influence market share and therefore inform targeting and messaging decisions.
• Maintaining relevance: Staying updated on which domains belong to which major provider helps in maintaining relevant and compliant sending practices.

Key opinions

• Incomplete nature: Experts confirm that no single list can capture every domain, given the sheer volume and continuous evolution of consumer and business domains managed by large providers.
• Strategic value: Despite their incompleteness, these domain lists remain valuable for broad segmentation and for rolling up traffic for queueing and deliverability management within Mail Transfer Agents.
• MX record approach: A more reliable method involves identifying which domains, particularly among the top millions on the internet, are mail-hosted by major providers through MX record analysis. This is a best practice for DNS lookups and subdomain usage.
• Market share estimates: Estimates suggest Gmail consistently holds the largest share (e.g., 65%), followed by Microsoft (e.g., 16%) and Yahoo (e.g., 13%), with Apple representing a growing segment (e.g., 1%).
• Evolving acronyms: The traditional MAGY (Microsoft, AOL, Gmail, Yahoo) acronym is evolving, with AOL often considered part of Yahoo and Apple replacing AOL as the 'A' due to its increasing relevance.

Key considerations

• Data complexity: Maintaining accurate and up-to-date lists of all domains is a significant data-related project due to ongoing changes and acquisitions.
• Audience segmentation: Understanding the demographic skew of users across different providers can inform more precise email marketing efforts.
• Apple's influence: Apple's growing impact, including domains like iCloud.com, me.com, mac.com, and its Private Relay feature, requires specific attention from senders. This is particularly relevant when emails bounce to Apple domains.
• Beyond consumer domains: It's important to remember that major providers also host numerous domains for small businesses and other entities, making total enumeration complex.

Key findings

• Explicit domain lists: Official support pages, such as Apple Support, often explicitly list common consumer domains like @icloud.com, @me.com, and @mac.com.
• Consolidated entities: Documentation confirms that historical domains (e.g., Hotmail, AOL) are now consolidated under larger entities (Microsoft, Yahoo/Oath), meaning policies apply across these grouped domains.
• New sender requirements: Recent updates from Google, Yahoo, and Microsoft (starting Feb 2024, expanding into 2025) mandate stricter authentication and low spam rates for senders targeting their domains.
• Private relay: Apple's iCloud Private Relay generates unique, randomized email addresses for users, affecting how senders perceive and manage these recipient domains.

Key considerations

• Policy updates: Regularly consulting official provider documentation is crucial, as policies, especially regarding bulk sending, are subject to frequent updates.
• Authentication standards: All major providers universally require robust email authentication protocols (SPF, DKIM, DMARC) for all associated domains to ensure messages reach the inbox. Our simple guide to DMARC, SPF, and DKIM can help.
• Bulk sender thresholds: Understanding the precise thresholds (e.g., 5,000 emails per day) that define a bulk sender for each provider's domains is critical for compliance.
• Domain reputation: Maintaining a positive sending reputation across all domains is paramount, as negative signals on one subdomain can impact others associated with the same provider. Understand your email domain reputation.