What are the challenges and benefits of using IPv6 for email deliverability?
Summary
What email marketers say10Marketer opinions
Email marketer from EmailDudes Forum shares that a challenge with IPv6 is the lower adoption rate among receiving mail servers, which necessitates maintaining IPv4 compatibility for broader reach.
Email marketer from Email Geeks notes that if deploying a new ESP platform, IPv6 should be configured properly and that domain reputation is more important than IP reputation when using IPv6.
Email marketer from SendGrid Blog explains that IPv6 provides a vastly larger address space, making it suitable for large-scale email sending operations, and reducing the need for complex IP rotation strategies.
Email marketer from MXToolbox states that using diagnostic tools to check IPv6 configuration, DNS records, and reverse DNS is essential for troubleshooting deliverability issues.
Email marketer from Mailjet Blog shares that IPv6 requires proper authentication (SPF, DKIM, DMARC) and a valid reverse DNS (PTR record) to avoid deliverability issues, similar to IPv4 but with potentially stricter enforcement.
Email marketer from StackOverflow states that a common pitfall with IPv6 email is not setting up the reverse DNS (PTR) record correctly, which can lead to immediate rejection by many receiving servers.
Email marketer from ReturnPath Blog shares that it is important to closely monitor IPv6 reputation as ISPs and blocklist providers may treat new IPv6 ranges with suspicion until a positive sending history is established.
Email marketer from Email Geeks shares that ideally, MTAs should be dual-stacked (support both IPv4 and IPv6) for maximum coverage, as not every receiving MX server supports IPv6.
Email marketer from SparkPost Blog explains that using IPv6 can improve deliverability by providing a larger IP address space, potentially reducing IP address sharing and reputation issues associated with IPv4.
Email marketer from Reddit explains that one of the main challenges with IPv6 is establishing a good IP reputation due to its vast address space and the potential for abuse. It requires consistent monitoring and proactive reputation management.
What the experts say5Expert opinions
Expert from Email Geeks mentions that IPv4 fallback is necessary because many servers do not support IPv6.
Expert from Email Geeks explains that IPv6 mailservers are modern and have higher expectations for DNS and authentication. However, decent ESPs should already meet these requirements.
Expert from Email Geeks shares that image and redirector hosting should be on dual-stack servers and that native IPv6 works better for some clients.
Expert from Word to the Wise responds that IPv6 environments often necessitate stronger authentication practices, including strict SPF, DKIM, and DMARC policies, to combat spam and abuse.
Expert from SpamResource explains that building a solid reputation on IPv6 requires patience and consistent sending practices, as many systems initially distrust new IPv6 ranges.
What the documentation says5Technical articles
Documentation from Google Workspace Admin Help specifies that to send email to Gmail users via IPv6, the sending server must have a valid PTR record (reverse DNS) that matches the hostname of the sending server, and the sending domain must pass SPF or DKIM authentication. This prevents spammers from using IPv6 addresses.
Documentation from CloudFlare shares that configuring DNS records (AAAA records for IPv6 addresses) correctly is crucial for IPv6 email deliverability. Incorrect DNS configuration can lead to deliverability issues.
Documentation from Microsoft explains that Exchange Server supports IPv6, but it's important to configure the server correctly to ensure proper mail flow. Issues can arise if IPv6 is enabled but not properly configured.
Documentation from RFC Editor details the original SMTP protocol specification, establishing a foundation for how email is transmitted over networks, including the subsequent adaptations for IPv6.
Documentation from IETF explains the technical challenges of transitioning to IPv6, including the need for dual-stack implementations and transition mechanisms to ensure compatibility with existing IPv4 infrastructure.