---
title: "Reply to a mail message"
method: POST
path: "/mail/v1/inboxes/{inboxId}/messages/{messageId}/reply"
tags: ["Agents"]
---

# Reply to a mail message

`POST /mail/v1/inboxes/{inboxId}/messages/{messageId}/reply`

Reply to a message in an inbox owned by the authenticated organization.

## Path parameters

- `inboxId` string, required
- `messageId` string, required

## Response `202`

Reply accepted for delivery

## Other responses

- `401` — Invalid API key
- `403` — Write access required
- `404` — Message or inbox not found

## Changes

- **2026-03-16** `20c3468a7d4a` — 1 info
  - endpoint added

[Change history](https://skmtc.dev/casemark/apis/case-dev-api/changes/mail/v1/inboxes/:inboxId/messages/:messageId/reply/post.md)

---

[API](https://skmtc.dev/casemark/apis/case-dev-api.md) · [All operations](https://skmtc.dev/casemark/apis/case-dev-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/casemark/case-dev-api/revisions/5b7e64e6d6f9/schema)