Summary
Obtaining a comprehensive list of subdomains for major email providers (Google, Microsoft, Yahoo, and Apple) is challenging, as indicated by experts, email marketers, and official documentation. While resources like Spamresource offer partial lists and market share estimations, and specific examples (e.g., mail.google.com, outlook.live.com, icloud.com) are known, no complete, officially maintained list exists. These subdomains are used for various functions, including web interfaces, tracking, and security. Understanding subdomains can aid in email list segmentation and improve deliverability. MX records play a critical role in email routing to the correct domains or subdomains.
Key findings
- No Official List: Major email providers do not provide a complete, public list of their subdomains.
- Partial Lists Exist: Some resources offer partial subdomain lists, but these are often incomplete.
- Market Share Data: Email market share is dominated by Gmail, with Yahoo showing some growth relative to Microsoft.
- Subdomain Usage: Subdomains are used for tracking, security, and various email service functions.
- MX Record Importance: MX records guide email routing.
Key considerations
- Data Incompleteness: Expect that available lists of subdomains are likely incomplete and may not be fully accurate.
- Dynamic Changes: Subdomain usage is subject to change by email providers.
- Deliverability Impact: Understanding subdomain usage can impact email deliverability strategies.
- Segmentation Opportunities: Subdomain insights can be used to enhance email list segmentation.
- Apple Privacy Changes: Apple's privacy changes might affect subdomain tracking and data.
What email marketers say
5 marketer opinions
Various email marketers on platforms like Reddit, StackExchange, Email Geeks, Email Marketing Forum, and Email Marketing Tips Blog have discussed the challenges and importance of understanding the subdomains used by major email providers. They generally agree that maintaining a comprehensive list is difficult due to the dynamic nature of these subdomains and their use for various tracking and security purposes. While some examples of subdomains (e.g., mail.yahoo.com, mail.google.com, outlook.live.com) are commonly known, a complete list is hard to compile. Understanding subdomains can help marketers better segment their email lists and improve targeting, as well as help in deliverability.
Key opinions
- Subdomain Tracking: Major email providers use numerous subdomains for tracking and security purposes.
- Incomplete Lists: Maintaining a complete and up-to-date list of subdomains is difficult.
- Segmentation Benefit: Understanding subdomains can help marketers segment email lists.
- Deliverability Impact: Understanding subdomains assists with better email deliverability.
Key considerations
- Dynamic Nature: Subdomains are dynamic and subject to change by email providers.
- Data Compilation: Compiling a complete list requires continuous monitoring and updates.
- Segmentation Strategy: Marketers should develop strategies for utilizing subdomain information for list segmentation.
- Provider Differences: Each major provider may have different subdomain structures and usage patterns.
Marketer view
Email marketer from Reddit user u/YahooFan123 shares that Yahoo uses subdomains like mail.yahoo.com and currently they do not use rocketmail.com but are more difficult to track comprehensively.
28 Jun 2021 - Reddit
Marketer view
Email marketer from Email Marketing Forum user EmailPro2000 discusses the importance of understanding subdomains for deliverability and provides examples of how providers like Gmail and Outlook use different subdomains for various services.
20 Apr 2023 - Email Marketing Forum
What the experts say
5 expert opinions
Experts from Email Geeks and Spamresource indicate that obtaining a comprehensive list of subdomains for major email providers is challenging. However, some resources provide partial lists or estimations. One expert is planning to release a list of the top 10 million domains hosted by MAGY (Microsoft, Apple, Google, Yahoo). Market share estimations were also provided, along with the observation that Yahoo's market share was growing while Microsoft's was shrinking. A dedicated list of Apple domains, including icloud.com, me.com, and mac.com, is available on Spamresource, along with MX records. A general reference list for MAGY providers exists but is not exhaustive.
Key opinions
- Partial Lists Available: While a complete list is difficult, partial lists of domains and subdomains exist.
- MAGY List in Progress: An expert is compiling a list of the top 10 million domains hosted by MAGY providers.
- Apple Domain List: A specific list of Apple email domains, including MX records, is available.
- Market Share Estimates: Market share estimations suggest Gmail dominates, followed by Hotmail and Yahoo, with Yahoo showing growth.
Key considerations
- Incomplete Data: Lists are likely incomplete and should be used as a starting point.
- Data Volatility: Market share and subdomain usage are subject to change.
- Resource Dependency: Rely on multiple resources to get a broader view.
- Apple-Specific Needs: Due to privacy changes made by apple, apple-specific knowledge should be considered.
Expert view
Expert from Spamresource shares a list of Apple email domains, including icloud.com, me.com, and mac.com. Provides the MX records for each domain.
16 Oct 2024 - Spamresource
Expert view
Expert from Email Geeks guesses the email market share is as follows: Gmail 65%, Hotmail 16%, Yahoo 13%, Apple just under 1%, Comcast just under 1%, Everything else 4%. Mentions that Yahoo was growing, and Microsoft was shrinking, last time he looked. Also questions how selling to men may skew the numbers.
15 Dec 2021 - Email Geeks
What the documentation says
5 technical articles
Official documentation from Google, Microsoft, and Apple confirms that major email providers utilize various subdomains for different services and functions. However, they do not provide comprehensive lists of these subdomains, citing their complexity and dynamic nature. IETF RFC 5321 clarifies the role of MX records in routing email to the correct subdomains or domains. Spamresource offers some information on domains from major providers, but this information is noted as potentially incomplete.
Key findings
- Subdomain Usage: Major email providers use multiple subdomains for diverse functions.
- No Complete Lists: Official providers do not publicly provide complete lists of their subdomains.
- MX Record Importance: MX records guide email routing to the correct subdomains.
- Limited External Resources: External resources may offer incomplete domain information.
Key considerations
- Dynamic Subdomains: Subdomains are likely to change over time.
- Technical Knowledge: Understanding MX records is crucial for comprehending email routing.
- Deliverability Focus: Understanding subdomain practices may help in email deliverability management.
- Resource Limitations: Expect limited official documentation on specific subdomains.
Technical article
Documentation from Apple Support explains that iCloud Mail primarily uses icloud.com, me.com, and mac.com domains, but additional subdomains may exist for specific functions. A comprehensive list is not publicly available.
11 Nov 2021 - Apple Support
Technical article
Documentation from Spamresource provides information on domains from Microsoft, AOL and Gmail. The information may be in-complete.
8 Mar 2023 - Spamresource
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