We migrated our email infrastructure to KumoMTA. Here's why it matters for you.

Postmark has transitioned from PowerMTA to KumoMTA, an open-source mail transfer agent (MTA) built for high-performance email delivery, to enhance their email infrastructure. This significant change aims to improve scalability and operational flexibility, addressing previous limitations in traffic management and manual scaling. KumoMTA, developed by email infrastructure veterans, allows for real-time traffic shaping and observability, providing Postmark with precise control over email delivery to major providers like Gmail, Yahoo, Microsoft, and Apple. The migration has resulted in faster queue times, translating to quicker email delivery, and maintains the sending reputation Postmark has built over 16 years. The adoption of KumoMTA, which is written in Rust and operates on modern cloud infrastructure, offers a robust foundation for future growth and feature development, ensuring that Postmark remains resilient and responsive to evolving email delivery requirements. While the bounce rates for Apple remain higher, this is attributed to Apple's unique email handling rather than an issue with KumoMTA. This infrastructure upgrade reflects Postmark's commitment to delivering emails efficiently and reliably, allowing clients to focus on their primary business objectives.