The lack of IPv6 delivery is causing real-world harm to downstream customers by preventing legitimate email from reaching your services.

IPv4 should increasingly be treated as a legacy access mechanism. Address space is limited, difficult to obtain in some environments, and particularly challenging for organizations and networks that are deploying IPv6-first infrastructure.

This is especially relevant for email delivery. Many cloud providers do not permit customers to use shared provider address space for outbound mail relay, largely because of the abuse and reputation challenges associated with cloud-hosted IP addresses. As an email service provider, I am sure you are familiar with these constraints.

Against that backdrop, the continued lack of IPv6 support is becoming a practical interoperability problem rather than simply a missing feature. I currently have multiple legitimate messages queued that cannot reach your services from users who are attempting to submit support requests. These are not hypothetical future concerns; the lack of IPv6 connectivity is already preventing communication between customers and your platform.

I would strongly encourage Mailgun to prioritize native IPv6 support for inbound and outbound mail delivery. At this point, IPv6 should be considered an essential part of modern Internet connectivity rather than an optional enhancement.

I am raising this as a feature request because I would much rather see the underlying interoperability issue resolved than have affected customers forced to find workarounds or alternative providers.

Please treat IPv6 support as a priority. The longer it remains unavailable, the more users and organizations operating on IPv6-only or IPv6-preferred networks will encounter preventable delivery failures.