Email API documentation

Your mailboxes — support@, sales@ — as an API.

Send from your own verified domain

Replies stay in the customer's thread

HTML, cc, bcc and attachments

Inbound email as JSON, with raw and safe HTML

Bounces and complaints blocked for you

Test mode that never sends

Forward your mailbox to IotaBot and verify your domain.

Create an API key with messages:send.

Send your first email:

POST/v1/messagesmessages:send

Send your first email

Request

curl -X POST "https://api.iotabot.com/v1/messages" \
  -H "Authorization: Bearer $IOTABOT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "channel": "email",
  "to": "priya@example.com",
  "from": "support@acme.com",
  "subject": "Your order #1042",
  "html": "<p>Hi Priya, your order shipped.</p>"
}' \
  -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

Retries are safe with an Idempotency-Key header. Give each message its own key (e.g. order-1042-shipped) and reuse it when you retry — a request with a key already seen returns the first result instead of sending again. Kept 24 hours.