Listmonk

Listmonk is a single-binary, high-performance newsletter manager written in Go. Bring your own SMTP. Excellent for technical operators who want full control.

An agent stack treats email as a two-way primitive. Inbound has to arrive as structured JSON a tool call can consume, sends have to be safe to retry when a model loop repeats itself, and every action needs an audit trail. A provider without inbound parsing only solves half the problem.

Against inbound parsing into tool calls and model-generated sends that must not duplicate, Listmonk covers webhook coverage, event stream, and batch sending, and does not cover inbound parsing, idempotency keys, SDK breadth, and multi-tenant support. Whether that gap matters depends on how central those are to the build.

• Inbound parsing: No
• Idempotency keys: No
• Webhooks: Yes
• Operating since: Not published
• Event stream: Yes
• Best published rate per 1,000: Tiers not published in comparable form
• Batch sending: Yes
• SDKs: None
• Multi-tenant: No

Inherits the deliverability of whichever SMTP relay you point it at.

Technical operators who want a self-hosted newsletter platform.