# Function: inboxTopic()

```ts
function inboxTopic(sign): Promise<string>;
```

Defined in: [packages/core/src/inbox/inbox.ts:188](https://github.com/leifriksheim/minca/blob/main/core/src/inbox/inbox.ts#L188)

The mailbox topic of an inbox: a hash of its signing key. A relay can't tell
whose inbox it is, and can check that whoever clears it holds that key.

## Parameters

| Parameter | Type |
| ------ | ------ |
| `sign` | `string` |

## Returns

`Promise`\<`string`\>