What are some examples of old or unusual email domains found in databases?

Key findings

• Longevity of accounts: Many users maintain email addresses for decades, including those from providers that no longer exist or have been absorbed into larger entities. This highlights the enduring nature of email as a communication tool.
• Historical ISP domains: Old domains often belong to internet service providers that were prominent in the 90s and early 2000s, such as webtv.net, freeserve.co.uk, or rocketmail.com. These act as digital archaeological finds.
• Acquired services: Some domains, like googlemail.com, are remnants of rebrands or mergers, still active but less common than their current counterparts (e.g., gmail.com). For more on common domains, see large free email providers.
• Data breach insights: Large-scale data breaches often reveal a mix of current and older domains, reflecting the long history of compromised data. One notable example is the Collection #1 data breach, which exposed billions of records.
• Edu domains persistence: Educational (.edu) domains often remain active for very long periods, as alumni continue to use their university email addresses years after graduation.

Key considerations

• Data quality: When encountering very old domains, it's crucial to assess the overall data quality. Many old email addresses may be defunct, leading to high bounce rates if used for sending.
• Deliverability impact: Sending to old or unverified lists containing such domains can negatively impact your sender reputation and email deliverability. Consider the issues with very old email lists.
• Spam trap risk: Old or unusual domains are sometimes repurposed as spam traps. Sending to these can lead to your IP or domain being added to a blocklist.
• Domain validity checks: It's essential to perform robust validation checks on all email addresses, especially those with less common or older domains, to ensure they are still active and receive mail.

Key opinions

• Nostalgia factor: Many marketers find it interesting to see how long people hold onto old email accounts, recognizing domains from their own early internet days.
• Data quality assessment: The discovery of old domains often prompts questions about the age and validity of the entire database, leading to efforts to cleanse lists.
• Legacy system insight: Marketers recognize that these domains point to a time when different email providers and services were prevalent, influencing how email infrastructure evolved.
• Engagement challenges: While intriguing, old addresses can pose a challenge for engagement metrics if the recipients are no longer active on those accounts. For more on engagement, see our guide to increasing click-through rates.

Key considerations

• List hygiene: Marketers must prioritize regular list hygiene to remove invalid or inactive old domains. This prevents high bounce rates and protects sender reputation.
• Avoiding spam traps: Old domains, especially those from defunct providers, are prime candidates for becoming spam traps. Marketers should be cautious and validate these addresses. Learn how to identify suspicious email domains.
• Segmentation: Consider segmenting older contacts or those with unusual domains into re-engagement campaigns or specific verification flows. This can improve overall deliverability for your main lists.
• Domain parsing: Ensure your systems can correctly parse and handle all types of valid email domains, no matter how old or unusual. For insights into valid address syntax, refer to relevant resources on email address best practices.

Key opinions

• Data longevity: Experts acknowledge that email addresses, and the domains they reside on, can persist for a very long time, often outliving the services themselves. This requires continuous monitoring of database quality.
• Spam trap indicators: Old or unrecognized domains are frequently recycled into spam traps by ISPs and blocklists, posing a significant threat to sender reputation.
• Deliverability risk: Sending to email addresses on very old or defunct domains significantly increases bounce rates and can negatively impact inbox placement, potentially leading to listing on a blocklist.
• Historical context: Some experts view these domains as historical artifacts that show the evolution of internet infrastructure and email service provision.

Key considerations

• Proactive list cleaning: It is crucial to regularly clean email lists, specifically targeting old, unengaged, or unusual domains, to prevent deliverability issues. This includes identifying email domains marketers should avoid.
• Domain validation tools: Utilize robust email validation services to verify the existence and deliverability of addresses on older or obscure domains before sending. This can prevent bounces due to non-existent domains.
• Reputation management: Continuously monitor your sender reputation and blocklist status, as old data is a common source of problems. Understand how to fix email deliverability issues for a proactive approach.
• Compliance with standards: Even with old domains, ensure compliance with email sending standards (e.g., SPF, DKIM, DMARC) to prove legitimacy. See DMARC implementation best practices for further guidance.

Key findings

• Domain registration longevity: WHOIS history records demonstrate that many domains, including those from old services, have been registered and active for over a decade, sometimes two decades or more. Data from WhoisXML API shows extensive historical data.
• Data breach composition: Large data breaches frequently aggregate email addresses from various historical sources, leading to the inclusion of domains from long-defunct or merged services. The Collection #1 breach is a prime example.
• RFC compliance vs. reality: While RFCs define email address syntax, real-world usage in old databases can sometimes deviate or include domains that reflect past internet norms. For more on this, see what RFC 5322 says vs. what actually works.
• Government and academic domains: Records often show the consistent presence of .gov and .edu domains over long periods, indicating their stable and enduring nature. A WIRED article highlighted the discovery of .gov domains in a large database.

Key considerations

• DNS records: Even for very old domains, their existence can often be verified by checking historical DNS (Domain Name System) records, specifically MX records, to see if they ever had mail exchange capabilities.
• TLD evolution: The presence of older or less common Top-Level Domains (TLDs) in databases reflects the evolving landscape of internet naming conventions. Some TLDs may also have higher associations with spam or reputation issues; consider which TLDs to avoid.
• Obsolete protocols: Some ancient domains might hint at underlying email protocols or configurations that are now obsolete, which could affect compatibility with modern sending systems.
• Data aggregation challenges: The sheer volume and age of data in compromised databases mean that identifying and classifying old or unusual domains is a complex task requiring sophisticated analytical tools.