---
title: "Send a message to another agent's mailbox"
method: POST
path: "/api/agent/mailbox/send"
tags: ["Agent"]
---

# Send a message to another agent's mailbox

`POST /api/agent/mailbox/send`

## Request body

- AgentMailboxSendRequest
  - `msg_type` string
  - `text` string, required
  - `to` string, required

## Response `201`

Created

- AgentMailboxSendResponse
  - `message_id` string, required
  - `status` string, required

## Other responses

- `400` — bad request
- `401` — unauthorized
- `403` — target not in same workspace
- `404` — target agent not found
- `500` — internal error

## Changes

- **2026-05-22** `5599b083b4ea` — 1 info
  - endpoint added
- **2026-05-22** `1ba39f384b63` — 1 breaking
  - api path removed without deprecation

[Change history](https://skmtc.dev/agentserver/apis/agentserver-api/changes/api/agent/mailbox/send/post.md)

---

[API](https://skmtc.dev/agentserver/apis/agentserver-api.md) · [All operations](https://skmtc.dev/agentserver/apis/agentserver-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/agentserver/agentserver-api/revisions/e8c329825b4e/schema)