Summary
Sending email from IPv4 to IPv6 recipients should not directly cause deliverability issues, provided that both sender and receiver are configured correctly, adhere to email protocols, and maintain a good IPv6 reputation. Dual-stack implementations are crucial for compatibility, as mail servers typically attempt IPv4 delivery if IPv6 fails. Configuration factors such as DNS records (A and AAAA), reverse DNS (rDNS), and network settings are essential for ensuring compatibility. Monitoring IPv6 address reputation, implementing IP warming for new IPv6 addresses, and ensuring sending infrastructure supports both IPv4 and IPv6 are vital for successful delivery. The increased address space of IPv6 requires vigilant anti-abuse measures and a focus on domain reputation.
Key findings
- Dual-Stack Implementation: Dual-stack implementations, supporting both IPv4 and IPv6, are a primary recommendation for ensuring compatibility.
- Correct IPv6 Configuration: Correctly configuring IPv6, including proper DNS records and network settings, is essential.
- Importance of IPv6 Reputation: A good IPv6 reputation is critical for deliverability, with poor reputation leading to delivery issues.
- rDNS Configuration: Proper reverse DNS (rDNS) configuration for IPv6 addresses is necessary.
- Anti-Abuse Measures: The vast address space of IPv6 requires strong anti-abuse measures.
- IP Warming for New IPs: IP warming practices are crucial for new IPv6 sending IPs.
- Potential for Higher Standards: Some mailbox providers may hold IPv6 sources to higher standards than IPv4, though this is becoming less prevalent.
Key considerations
- Implement Dual-Stack Support: Implement dual-stack support to ensure compatibility with both IPv4 and IPv6 recipients.
- Verify DNS Records: Regularly verify and maintain accurate DNS records, including A and AAAA records, for IPv6 addresses.
- Configure rDNS: Ensure correct rDNS configuration for IPv6 addresses.
- Monitor IPv6 Reputation: Implement monitoring tools to track IPv6 address reputation and quickly address any issues.
- Implement IP Warming: Employ a proper IP warming strategy when introducing new IPv6 addresses.
- Infrastructure Support: Ensure that your sending infrastructure supports both IPv4 and IPv6 protocols and connections.
- Authentication Protocols: Adhere to modern authentication protocols such as SPF, DKIM, and DMARC.
What email marketers say
11 marketer opinions
The consensus is that sending email from IPv4 to IPv6 recipients shouldn't inherently cause deliverability issues, provided both the sender and receiver are correctly configured and adhere to email protocols. However, the IPv6 address's reputation, proper DNS records (A and AAAA), and correct reverse DNS (rDNS) are crucial for ensuring compatibility and avoiding deliverability problems. IP warming for new IPv6 addresses and continuous reputation monitoring are also advised. Anti-abuse measures and varying IPv6 space sizes add complexities, emphasizing the importance of domain reputation.
Key opinions
- IPv6 Configuration: Correctly configured IPv6 infrastructure (including proper DNS records) is essential for compatibility.
- IPv6 Reputation: A good IPv6 reputation is vital for deliverability; poor reputation can lead to delivery issues.
- rDNS Importance: Correct reverse DNS (rDNS) entries for IPv6 addresses are crucial for establishing trust.
- IP Warming: IP warming practices are recommended for new IPv6 addresses to build a positive reputation.
- Dual Protocol Support: Ensuring sending infrastructure supports both IPv4 and IPv6 is beneficial.
- Monitoring Reputation: Monitoring IPv6 address reputation is necessary to identify and address potential issues proactively.
- Anti-Abuse and Space Size: IPv6 has a larger address space, making anti-abuse measures different and highlighting domain reputation as important.
Key considerations
- DNS Records: Verify and maintain accurate A and AAAA records for IPv6 addresses.
- rDNS Configuration: Configure and monitor reverse DNS (rDNS) to ensure it matches the sending domain.
- Reputation Monitoring: Implement monitoring tools to track IPv6 address reputation and address any issues promptly.
- IP Warming Strategy: Develop and implement an IP warming strategy for new IPv6 addresses, gradually increasing sending volume.
- Security Measures: Implement proper security protocols and follow industry best practices to avoid being flagged as spam.
- Infrastructure Support: Ensure that your sending infrastructure supports both IPv4 and IPv6 protocols.
Marketer view
Email marketer from MailChannels highlights the importance of having a good IPv6 reputation for deliverability. Monitoring tools are necessary.
2 Feb 2022 - MailChannels Blog
Marketer view
Email marketer from SparkPost shares that IPv6 should not directly impact email deliverability negatively. However, the reputation of the IPv6 address is important. Monitor and manage your IPv6 address reputation.
11 Jul 2024 - SparkPost Blog
What the experts say
11 expert opinions
While sending from IPv4 to IPv6 shouldn't inherently cause issues, several factors affect deliverability. Mail servers typically attempt IPv4 delivery if IPv6 fails. Setting up a working IPv6 network offers minor advantages, but IPv6 presents unique challenges. Some mailbox providers impose stricter standards on IPv6 sources. Google previously had higher IPv6 standards, now lessened. A successful IPv4 setup might fail on IPv6. IPv6 requirements differ from IPv4, making IPv6 harder. Previously, IPv6 had capacity advantages, but this is doubtful now. Correctly implementing IPv6, including rDNS, is crucial, and poor configuration or reputation causes problems. Monitoring IPv6 reputation and configuring rDNS correctly are essential for ensuring deliverability.
Key opinions
- IPv4/IPv6 Fallback: Mail servers generally attempt IPv4 delivery if IPv6 fails.
- IPv6 Challenges: Sending over IPv6 presents different challenges compared to IPv4, and some mailbox providers have higher standards.
- Configuration Importance: Correctly implementing IPv6 with proper rDNS is crucial to prevent deliverability problems.
- Reputation Matters: Maintaining a good IPv6 reputation is essential for successful delivery.
- Past IPv6 Advantage: Previously, IPv6 offered capacity advantages, making throttling less likely, but this is no longer the case.
Key considerations
- Dual-Stack Setup: Consider setting up a working IPv6 production network, though the advantages are minor.
- rDNS Configuration: Ensure rDNS is configured correctly for your IPv6 addresses.
- Reputation Monitoring: Monitor your IPv6 reputation to identify and address potential deliverability issues.
- Authentication Standards: Implement and adhere to robust authentication standards (SPF, DKIM, DMARC).
- Evolving Standards: Stay informed about changes and updates to IPv6 deliverability requirements from major mailbox providers.
Expert view
Expert from SpamResource explains that as long as you implement IPv6 correctly (including rDNS), sending from IPv4 to IPv6 recipients shouldn't be an issue. Incorrect IPv6 configurations and poor IPv6 reputation are the main causes for deliverability problems.
3 Nov 2022 - SpamResource
Expert view
Expert from Email Geeks explains that you can have a reasonable setup on IPv4 that delivers fine, but if you were to do the same thing on IPv6 it wouldn’t.
9 Sep 2022 - Email Geeks
What the documentation says
4 technical articles
The documentation consistently recommends dual-stack implementations as a key strategy for IPv6 transition, allowing mail servers to communicate using both IPv4 and IPv6 protocols. Proper configuration of IPv6 within email systems like Exchange and Postfix, along with accurate DNS records and network settings, is crucial for ensuring compatibility and preventing delivery issues to IPv6 recipients.
Key findings
- Dual-Stack is Key: Dual-stack implementations (supporting both IPv4 and IPv6) are the primary recommendation for ensuring compatibility.
- IPv6 Support: Major email systems like Exchange and Postfix support IPv6.
- Proper Configuration: Proper configuration of IPv6 within these systems is critical for preventing delivery issues.
- DNS Importance: Accurate DNS records are essential for successful IPv6 communication.
Key considerations
- Implement Dual-Stack: Adopt a dual-stack approach to support both IPv4 and IPv6.
- Configure IPv6 Properly: Ensure your email systems (e.g., Exchange, Postfix) are correctly configured for IPv6.
- Verify DNS Records: Double-check and maintain accurate DNS records, including AAAA records for IPv6.
- Network Settings: Review and adjust network settings to accommodate IPv6 communication effectively.
Technical article
Documentation from Postfix explains that Postfix supports IPv6. Configuration involves setting up the appropriate network interfaces and ensuring DNS records are correctly configured for IPv6 addresses.
22 Jan 2023 - Postfix Documentation
Technical article
Documentation from Cisco recommends dual-stack configurations for IPv6 transition. This ensures that systems can communicate over both IPv4 and IPv6 networks, maintaining compatibility.
7 Apr 2022 - Cisco Documentation
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