> ## Documentation Index
> Fetch the complete documentation index at: https://www.plain.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Reply to threads

<Snippet file="graphql/sdk-note.mdx" />

You can reply to a thread using the `replyToThread` mutation, as long as the thread's communication channel is either `API`, `CHAT`, `EMAIL`, `SLACK` or 'MS\_TEAMS'. 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`](/graphql/error-codes#cannot_reply_to_thread) and a message indicating why.

This operation requires the following permission:

* `thread:reply`

<Snippet file="graphql/reply-to-thread.mdx" />

## Impersonation

<Note>
  Impersonation is exclusively available in our `Grow` 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]\([https://plain.support.site/article/headless-portal-overview](https://plain.support.site/article/headless-portal-overview)).

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 theme={null}
{
  "impersonation": {
    "asCustomer": {
      "customerIdentifier": {
        "emailAddress": "blanca@example.com"
      }
    }
  }
}
```

<Note>
  Impersonation is only possible for `API`, `CHAT`, `EMAIL` and `SLACK` threads (based on the thread's `channel` field).
</Note>

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

* `SLACK`: the message will appear in Slack as a new message from the impersonated customer, including their name and any other customer details
* `API` and `EMAIL`: the message will be sent as an email with the impersonated customer's email address as the "From" address, making it appear as if they sent the email directly
* `CHAT`: the message will appear in the thread as coming directly from the impersonated customer, with their name and avatar displayed

When replying to an `EMAIL` or `API` thread, you can optionally add 'Cc' and 'Bcc' recipients by using the `channelSpecificOptions` parameter:

```graphql theme={null}
{
  "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`

<Snippet file="graphql/reply-to-thread-impersonation.mdx" />