> ## Documentation Index
> Fetch the complete documentation index at: https://plain-mattvagni-patch-1.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Reply to threads

You can reply to a thread using the `replyToThread` mutation, as long as the thread's communication channel is either `EMAIL` or `SLACK`. This information is available in the thread as the `channel` field.

If it is not possible to reply to a thread, you will get the mutation error code [`cannot_reply_to_thread`](/api-reference/graphql/error-codes#cannot_reply_to_thread) and a message indicating why.

This operation requires the following permission:

* `thread:reply`

<Tabs>
  <Tab title="Typescript SDK">
    <Snippet file="typescript-sdk/reply-to-thread.mdx" />

    Where `res.data` is:

    <Snippet file="typescript-sdk/reply-to-thread-response.mdx" />
  </Tab>

  <Tab title="GraphQL">
    <Snippet file="graphql/reply-to-thread.mdx" />
  </Tab>
</Tabs>

## Impersonation

<Note>
  Impersonation is exclusively available in our `Scale` plan. You can see all available plans in our
  [pricing page](https://www.plain.com/pricing).
</Note>

This feature allows you to bring native messaging between your customers and Plain, straight into [your own product](/headless-support-portal).

With impersonation, you can reply to a thread on behalf of one of your customers: impersonated messages will show up as if they were sent by the customers themselves.

In order to impersonate a customer, provide the `impersonation` parameter in the `replyToThread` mutation, specifying the identifier of the customer you want to impersonate. You can pick any of the available customer identifiers (`emailAddress`, `customerId` or `externalId`)

```graphql
{
  "impersonation": {
    "asCustomer": {
      "customerIdentifier": {
        "emailAddress": "blanca@example.com"
      }
    }
  }
}
```

The customer message will be processed differently based on the thread's channel:

* `SLACK`: a new Slack message will be sent to the thread, using the customer's details
* `EMAIL`: an email will be sent to the thread, where the sender will be your customer

When replying to an `EMAIL` thread, you can optionally add 'CC' and 'BCC' recipients by using the `channelSpecificOptions` parameter:

```graphql
{
  "channelSpecificOptions": {
    "email": {
      // For CC'd recipients
      "additionalRecipients": [
        {
          "email": "peter@example.com",
          "name": "Peter"
        },
      ],
      // For BCC'd recipients
      "hiddenRecipients": [
        {
          "email": "finance@example.com"
        }
      ]
    }
  }
}
```

This operation requires the following permissions:

* `thread:reply`
* `customer:impersonate`

<Tabs>
  <Tab title="Typescript SDK">
    <Snippet file="typescript-sdk/reply-to-thread-impersonation.mdx" />
  </Tab>

  <Tab title="GraphQL">
    <Snippet file="graphql/reply-to-thread-impersonation.mdx" />
  </Tab>
</Tabs>