Write a reply

Write an outbound message into an existing thread. Saved as a draft by default; with send: true it is queued and the launcher sends it after the suppression check and the send gate. A refused message comes back as blocked with the reason. Cannot start a conversation.

POSThttps://app.trygtm.com/api/v1/conversations/{conversation_id}/messages

Scope: write
MCP tool: draft_reply

Path parameters

conversation_idstringrequired: The thread to reply on.

Headers

Idempotency-Keystringoptional: A key unique to this write, up to 255 characters. A retry carrying the same key returns the first response instead of running again. Kept for 24 hours.

Body

bodystringrequired: The message text.
subjectstringoptional: Email only. Defaults to the thread's subject.
sendbooleanoptionaldefault: false: Release it for sending instead of saving a draft.

Request

curl -X POST https://app.trygtm.com/api/v1/conversations/8f2a91c4-6d1e-4c0a-9a57-2f3b1c7e9d10/messages \
  -H "Authorization: Bearer $TRYGTM_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{
    "body": "Tuesday at 10 works. I'll send an invite."
  }'

Response

{
  "data": {
    "id": "aa11bb22-cc33-4d44-8e55-ff6677889900",
    "conversation_id": "0f1e2d3c-4b5a-4697-8877-665544332211",
    "direction": "outbound",
    "channel": "email",
    "kind": "message",
    "status": "drafted",
    "subject": "Re: routing software",
    "body": "Tuesday at 10 works. I'll send an invite.",
    "gate_result": null,
    "error": null,
    "created_at": "2026-09-18T10:15:00.000Z",
    "updated_at": "2026-09-18T10:15:00.000Z"
  }
}