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github.com/KumoCorp/kumomta @2026.06.23-f3af1cd0

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repository ↗ · DeepWiki ↗ · release 2026.06.23-f3af1cd0 ↗ · + Follow
4,453 symbols 16,451 edges 355 files 612 documented · 14% updated 4d ago2026.06.23-f3af1cd0 · 2026-06-23★ 50658 open issues

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Functions 3,617 Types & classes 836
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README

KumoMTA

KumoMTA is an open-source Message Transfer Agent (MTA) designed for high-performance outbound email functionality, similar to commercial enterprise MTAs such as Momentum, PowerMTA, and Halon.

The KumoMTA project was founded by a group of email industry veterans with decades of experience building and managing high-performance On-Prem MTAs and is supported by a community of some of the largest senders in the world.

Because it is designed for high-performance sending environments, KumoMTA is for experienced email operations professionals who are accustomed to high-performance sending environments and familiar with DevOps practices.

Learn more in our FAQ and at https://kumomta.com/.

Documentation

You can learn more about KumoMTA from the Documentation.

Community

Real-time discussion is available on Our Discord.

Developers

If you are interested in contributing/extending KumoMTA, take a look at DEVELOPERS.md. The #devel channel on Our Discord is for contributors to discuss KumoMTA development.

Reporting Bugs

See How to Report Bugs.

Getting Help

See How to Get Help. Issues are for features and bugs only, any help requests posted to Issues will be closed. For paid support see https://kumomta.com/support.

Getting Updates

You can subscribe to updates at https://kumomta.com/subscribe, we send updates periodically and will never sell nor share your information.

Talk to Us

We're available to talk about the project, book us at https://cal.com/team/kumomta/talk-with-kumomta.

Extension points exported contracts — how you extend this code

Core symbols most depended-on inside this repo

Shape

Method 1,955
Function 1,662
Class 635
Enum 180
Interface 21

Languages

Rust100%
Python1%
TypeScript1%

Modules by API surface

crates/rfc5321/src/parser.rs242 symbols
crates/mailparsing/src/rfc5322_parser.rs188 symbols
crates/message/src/message.rs149 symbols
crates/kumod/src/smtp_server.rs84 symbols
crates/kumod/src/ready_queue.rs76 symbols
crates/mailparsing/src/mimepart.rs71 symbols
crates/kumo-api-types/src/shaping.rs71 symbols
crates/integration-tests/src/kumod.rs63 symbols
crates/maildir/src/lib.rs56 symbols
crates/config/src/lib.rs55 symbols
crates/rfc5321/src/client.rs54 symbols
crates/message/src/timeq.rs52 symbols

For agents

$ claude mcp add kumomta \
  -- python -m otcore.mcp_server <graph>

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