# OR43 - Create a thread on an order

Each message has a 30 Megabyte size limit, regardless of the number of attachments in the message.Call FrequencyRecommended usage: At each new thread posted on an orderMaximum usage: At each new thread posted on an order

Endpoint: POST /api/orders/{order_id}/threads

## Path parameters:

  - `order_id` (string, required)
    Identifier of the order on which the thread is created

## Query parameters:

  - `shop_id` (integer)
    Use this parameter when your user has access to several shops. If not specified, the shop_id from your default shop will be used.

## Request fields (multipart/form-data):

  - `files` (array)
    List of attachments for the first message of the thread

  - `thread_input` (object, required)
    Thread content: body, topic, participants...

  - `thread_input.body` (string, required)
    Message body

  - `thread_input.to` (array, required)
    Message recipients
    Enum: "OPERATOR", "SHOP", "CUSTOMER"

  - `thread_input.topic` (object, required)
    Thread topicThe topic can either have a free or a fixed value depending on the topic type

  - `thread_input.topic.type` (string, required)
    Topic type
    Enum: "FREE_TEXT", "REASON_CODE"

  - `thread_input.topic.value` (string, required)
    Topic value

## Response 201 fields (application/json):

  - `message_id` (string, required)
    Id of the first message created on the thread

  - `thread_id` (string, required)
    Id of the created thread