The overwhelming consensus from experts, marketers, and documentation sources is that a comprehensive, static list of all mailbox providers and their domains is unattainable due to the ever-changing email landscape, acquisitions, domain consolidations, and the sheer volume of domains. The most effective strategies involve building and dynamically adapting your own lists, focusing on major ISPs, understanding their specific policies and authentication requirements, monitoring engagement and bounce messages, and segmenting your audience based on their domains. Attempting to scrape MX records is discouraged unless performed ethically and responsibly. Relying on external services or pre-built lists is likely to result in outdated or incomplete information. Direct, authoritative lists don't exist, but IANA provides a list of TLDs, and insight can be gained from the postmaster tools of major providers.
11 marketer opinions
The consensus is that a comprehensive, static list of all mailbox providers and their domains is practically impossible to maintain due to constant changes, the vast number of domains, and the dynamic nature of email infrastructure. Instead, the advice centers around focusing on major providers, monitoring engagement and bounces, segmenting your own data, and building custom lists based on your specific audience. Relying on external services is not an advisable strategy.
Marketer view
Email marketer from StackExchange explains that compiling a full list of email domains is an impossible task, and suggests focusing on largest domains and using DNS queries to determine email acceptance on a case-by-case basis. Mentions that many domains use external services so MX records are not a good way of figuring out the details.
3 Jan 2025 - StackExchange
Marketer view
Email marketer from Reddit shares that maintaining a list is difficult, and suggests scraping MX records using tools or scripts but to do it ethically and with respect to rate limits. Also warns that you might need to keep the lists yourself
30 May 2022 - Reddit
6 expert opinions
Experts agree that obtaining a comprehensive and static list of all mailbox providers and their domains is highly impractical, if not impossible. The landscape is constantly evolving due to acquisitions, domain consolidations, and the sheer volume of domains. The recommended approach involves building and adapting your own lists, focusing on major ISPs, understanding their policies, monitoring bounce messages, and segmenting based on your sending data. Collecting data using SMTP banners is discouraged due to potential abuse complaints. A focus on active monitoring and dynamic adaptation is key.
Expert view
Expert from Word to the Wise (Laura Atkins) emphasizes that a complete, static list of email domains is impossible to maintain. Instead, she advises focusing on monitoring your own sending data to identify the domains your recipients are using and segmenting your lists accordingly. She highlights the importance of using feedback loops and other monitoring tools to identify and address deliverability issues with specific domains.
4 Mar 2025 - Word to the Wise
Expert view
Expert from Email Geeks explains that with Yahoo, Google, and Microsoft’s corporate offerings and also lots of legacy, absorbed, consolidated and acquired domains, the best such a system could hope for would be to tell you is who answers when you knock.
16 Jan 2023 - Email Geeks
5 technical articles
While a direct list of all mailbox providers and their domains is unavailable through these documentation sources, they offer valuable tools and insights. IANA provides a list of all valid domain extensions (TLDs). Google and Microsoft offer guidelines and insights into their own email infrastructures. MXToolbox provides tools to look up MX records to identify mail servers. RFCs offer standards for email deliverability.
Technical article
Documentation from Google Postmaster Tools provides guidelines for bulk email senders and includes information about Google's email infrastructure. While it doesn't offer a full list, it provides insights into how Google handles email and the domains they use.
29 Dec 2021 - Google Postmaster Tools
Technical article
Documentation from MXToolbox explains how to use their tools to look up MX records for specific domains. While they don't provide a full list, their tools can be used to identify the mail servers (and thus, potentially, the email providers) for given domains.
22 Feb 2022 - MXToolbox
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