# Message moderation mechanism (/en/realtime-media/im/build/moderate-and-manage-client-behavior/moderation-mechanism)

> For AI agents: see the complete documentation index at [llms.txt](/llms.txt).

During message moderation, the content moderation service reviews the specifically designated fields within the message `bodies`. Different message types have different field names and content structures. Ensure these fields contain only the content to be moderated, as other content may affect moderation accuracy. This guide describes the message content fields within the `bodies` for each message type.

Following is a sample message structure:

```json
{
  "msg_id": "5I02W-XX-8278a",
  "timestamp": 1403099033211,
  "direction": "outgoing",
  "to": "XXXX",
  "from": "XXXX",
  "chat_type": "chat",
  "payload": {
    "bodies": [
      {
        // message body details 
      }
    ],
    "ext": {
      "key1": "value1"
      // more key-value pairs 
    },
    "from": "XXXX",
    "to": "XXXX"
  }
}
```

## Text messages [#text-messages]

For text messages, the content moderation service only reviews the content in the `msg` field within the message `bodies`.

| Parameter | Type   | Description      |
| :-------- | :----- | :--------------- |
| `msg`     | String | Message content. |

Example:

```json
{
  "bodies": [
    {
      "msg": "welcome to Agora Chat!",
      "type": "txt"
    }
  ]
}
```

## Image messages [#image-messages]

For image messages, the content moderation service downloads files from their URLs for review. The service focuses on the `url` field within the `bodies` of these messages.

| Parameter | Type   | Description                       |
| :-------- | :----- | :-------------------------------- |
| `url`     | String | URL address of the image message. |

Image message `bodies` example:

```json
{
  "bodies": [
    {
      "file_length": 128827,
      "filename": "test1.jpg",
      "secret": "DRGM8OZrEeO1vaXXXXXXXXHBeKlIhDp0GCnFu54xOF3M6KLr",
      "size": {
        "height": 1325,
        "width": 746
      },
      "type": "img",
      "url": "https://XXXX/XXXX/chatdemoui/chatfiles/65e54a4a-XXXX-XXXX-b821-ebde7b50cc4b"
    }
  ]
}
```

## Custom messages [#custom-messages]

<CalloutContainer type="info">
  <CalloutDescription>
    To use custom message moderation, [Enable the moderation feature](/en/realtime-media/im/reference/console/content-moderation-microsoft#enable-the-moderation-feature) in [Agora Console](https://console.agora.io/), then [contact technical support](mailto\:support@agora.io) to enable custom message moderation.
  </CalloutDescription>
</CalloutContainer>

For custom messages submitted for moderation, the `customExts` parameter must include a `moderation` node, as shown in the following example:

```json
{
  "customExts": {
    "moderation": {
      "enable": true,
      "contents": [
        {
          "type": "text",
          "data": "Hello World"
        }
      ]
    }
  }
}
```

The parameters in the `moderation` node are described in the following table:

| Parameter  | Type    | Description                                                                                                                              |
| :--------- | :------ | :--------------------------------------------------------------------------------------------------------------------------------------- |
| `enable`   | Boolean | Whether to enable moderation. - Set to `true` to enable moderation. - Set to `false` to disable moderation.                              |
| `contents` | Array   | Message content.                                                                                                                         |
| `type`     | String  | Message type. Currently, the moderation service supports only text and image messages, so this field can only be set to `text` or `img`. |
| `data`     | String  | Content to be moderated. - For text messages: the actual message content. - For image messages: the image URL.                           |