Break Free of the Commercial Licensing Trap

Get Started GET UPDATES Join our Community Talk To Us
My project (3)

We do things differently...

KumoMTA is Open-Source. No license fees upfront or ever. The software will always be free to use, review, and modify as you see fit.

It’s time to say goodbye to the cycle of ever-increasing prices imposed by commercial MTA vendors, with licensing terms increasing in price and complexity year after year.

While Open-Source MTA technology hasn't historically been a good fit for high-volume senders, KumoMTA is the first Open-Source MTA built from the ground-up for high-volume senders, by industry experts.


High Performance

KumoMTA was built for large-scale senders, who need high throughput to meet their customer’s needs.
KumoMTA is designed to provide industry-leading performance, saturating physical hardware, while ensuring that your messages are safely queued to prevent message loss or double-sending.

Highly Flexible

KumoMTA presents a solution for modern enterprises, with full real-time integration capabilities for configuration, message manipulation, and routing via its built-in policy engine and data source access. Businesses can adapt their MTA to fit their environment's needs and not the other way around.

Modern Architecture

We’ve designed KumoMTA to be a native part of your cloud or modern on-prem architecture. From APIs & webhooks to AMQP, containers and native support for both SOCKS5 and HAProxy forward proxies, KumoMTA is not a black box but a fully integrated component of your DevOps environment.

Fully Supported

Senders need a platform they can depend on, from a company they can trust. Support for KumoMTA is available directly from the team that built it, protected by a 24/7 response SLA.
We're ready to help you every step of the way, by phone and email.

Cloud Friendly

Are you looking to move your email infrastructure to your cloud? Kumo is the Japanese word for Cloud, and we chose that name for a reason.
Our North Star is to support senders moving to their own public and private cloud environments at scale.

We're Here to Help

Whether you're migrating to Open-Source, standing up a greenfield environment, or need remote management, our Professional Services team is experienced in all aspects of on-prem email infrastructure.
Our services packages provide as much (or as little) help as your unique needs require.

Proudly Supported By

Free for all, thanks to our supporters.

Our Partners


Integration Partner

Ongage is an email marketing platform that helps your business to personalize engagements and drive conversions through data.
Learn More

Deliverability Partner

Postmastery is a leader in email deliverability and infrastructure management. They offer professional tools for email delivery and monitoring, enabling legitimate email senders to optimize their infrastructure and practices for email marketing and transactional email applications.
Learn More


Latest Post

Happy Birthday KumoMTA!

High Volume Email on Microsoft?

AboutMyEmail Testing Tool