---
title: "Start new outbound (Tier2+ policy-gated)"
method: POST
path: "/v1/send"
tags: ["Outbound"]
---

# Start new outbound (Tier2+ policy-gated)

`POST /v1/send`

## Request

- Base URL: `https://api.thrd.email`
- URL: `https://api.thrd.email/v1/send`
- Auth: HTTP bearer

## Headers

- `Idempotency-Key` string, required

## Request body

- object
  - `inbox_id` string, uuid, required
  - `to` string, email, required
  - `subject` string, required
  - `text` string
  - `html` string
  - `grant_token` string
  - `consent_token` string: Deprecated and ignored. Recipient consent is confirmed through a recipient-only link and resolved from durable state.
  - `por_token` string: PoR token provided by server when required.
  - `por_answer` string: PoR answer for provided por_token.
  - `source_message_id` string, uuid: Optional inbound message context used for prompt-injection policy gating.
  - `security_ack_token` string: Required on Tier 2/3 when source_message_id has high prompt-injection risk. Obtain via POST /v1/security/ack.

## Response `202`

Accepted

## Other responses

- `400`: Bad request
- `403`: Plan/policy blocked
- `409`: Same key reused with different payload
- `428`: Proof of Reasoning or Security Ack required
- `429`: Rate limit or outbound entitlement reached

---

[API](https://skmtc.dev/thrd/apis/thrd-agent-email-api.md) · [All operations](https://skmtc.dev/thrd/apis/thrd-agent-email-api/llms.txt) · [OpenAPI document](https://skmtc.dev/thrd/apis/thrd-agent-email-api/revisions/d8a88129cd34?raw)