curl --request POST \
  --url https://api.conduit.ai/v1/tickets/{id}/messages \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "body": "Hi there, can you confirm check-in time?",
  "attachments": [
    {
      "attachment_id": "kg2a8d8w8zv1m9q9f9h7e3b2n97j6x2c",
      "name": "failed-contacts.csv",
      "content_type": "text/csv",
      "content_length": 18432
    }
  ]
}
'

{
  "data": {
    "id": "yh7t5azsr0zpfpyf67vtce0j6n844y1e",
    "workspace_id": "j57demo8f8x7c9v0n2q4r6t8y1u3i5o",
    "conversation_id": "ph77c0dy0mgdpzmqz6tesry8w184002s",
    "ticket_id": null,
    "channel": "unthreaded_email",
    "status": "sent"
  }
}