# M12 - Reply to a thread

Maximum of 1000 messages on a threadCall FrequencyRecommended usage: Synchronous only - At each thread answerMaximum usage: Synchronous only - At each thread answer

Endpoint: POST /api/inbox/threads/{thread_id}/message

## Path parameters:

  - `thread_id` (string, required)
    The ID of the thread to reply to.

## 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 messageMaximum 50 across all threads of the same entity.For example, for a given order, you can not have more than 50 attachments across all its threads.

  - `message_input` (object, required)
    The message data

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

  - `message_input.to` (array, required)
    List of recipients of the message

  - `message_input.to.id` (string)
    Participant id

  - `message_input.to.type` (string, required)
    Participant type
    Enum: "OPERATOR", "SHOP", "CUSTOMER"

  - `message_input.topic` (object)
    New topic for the thread. Leave empty if you don't want to update it.

  - `message_input.topic.type` (string)
    Enum: "FREE_TEXT", "REASON_CODE"

  - `message_input.topic.value` (string)

## Response 201 fields (application/json):

  - `message_id` (string)
    Id of the message

  - `thread_id` (string)
    Id of the thread