Reply to an email in the same thread via API

Reply with conversation_id — In-Reply-To and References are set for you.

POST/v1/messagesmessages:send

Reply

Request

curl -X POST "https://api.iotabot.com/v1/messages" \
  -H "Authorization: Bearer $IOTABOT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "conversation_id": "6a4b9e21c3f1a2b3c4d5e6f7",
  "text": "Thanks — we have refunded the difference."
}' \
  -H "Idempotency-Key: order-1042-shipped"

Response · 202

{
  "data": {
    "id": "6a4ba0f1c3f1a2b3c4d5e733",
    "object": "message",
    "status": "queued",
    "channel": "email",
    "conversation_id": "6a4b9e21c3f1a2b3c4d5e6f7",
    "created_at": "2026-10-01T09:16:10.004Z",
    "type": "email",
    "email": {
      "subject": "Order #1042",
      "mailbox": "support@acme.com",
      "customer": "priya@example.com",
      "message_id": "<0102019a1c.iotabot@acme.com>",
      "thread_id": "<CAF3kq1x@mail.gmail.com>",
      "from": "support@acme.com",
      "to": [
        "priya@example.com"
      ],
      "cc": [],
      "in_reply_to": "<CAF3kq1x@mail.gmail.com>",
      "references": "<CAF3kq1x@mail.gmail.com>"
    }
  }
}

Errors

conversation_closedintegration_pausedsender_not_verifiedsender_not_foundrecipient_suppressedrecipient_unsubscribedfile_already_usedattachments_too_largeapi_quota_exceededidempotency_key_reusedidempotency_in_progress