# authenticate

URL: /business/nouns/domain/authenticate · Id: `verb:Domain.authenticate` · Call: `await $.Domain.authenticate({ … })` (SDK) or the `do` tool at `https://api.sb/mcp`. Inputs says what to pass, Outputs what returns, When it waits who approves.

> Authenticate writes a Domain’s SPF, DKIM and DMARC records and verifies them before its first send.

Authenticate writes a [Domain](/business/nouns/domain)’s SPF, DKIM and DMARC records and verifies them before its first send.

## Inputs
| Input | Type | Required | Description |
| --- | --- | --- | --- |
| `domain` | [Domain](/business/nouns/domain) | Yes | The sending Domain. |
| `dmarc` | `string` | No | The DMARC policy; it starts at `none` with reports and tightens to `quarantine`. |

## Outputs
| Output | Type | Required | Description |
| --- | --- | --- | --- |
| `domain` | [Domain](/business/nouns/domain) | Yes | The Domain, authenticated. |

## Effects
- Emits [`Domain.authenticated`](/business/events/Domain.authenticated).
- Performed by the [Security Engineer](/agents/engineering/security-engineer).
- Two-way: it runs at once, in the `try`, `send` and `do` modes.
- Refuses every send from the Domain until all three records verify.
- Cold outbound sends only from secondary Domains, never the Domain receipts use.

## Refuses when
| Check | Error | Fix | Then call |
| --- | --- | --- | --- |
| The key is valid, but its scopes do not allow this operation. | [`forbidden`](/code/api/errors/forbidden) | Use a key whose scopes cover the operation, or ask an owner of the namespace to grant them. | [Domain.authenticate](/business/nouns/domain/authenticate) |

## When it waits
| Gate | Default |
| --- | --- |
| Decision class | Low: two-way, nothing at stake |
| [Delay window](/systems/trust-and-governance/controls/one-way-windows) | None: it runs once review passes. |
| Limit | The call [Limit](/business/nouns/limit) of the [Permission](/business/nouns/permission) it runs under. |
| Over the Limit | It waits `pending` for an [Approval](/business/nouns/approval) from the [Founder](/agents/founding/founder). Approved, it runs; refused, it ends `refused` with [`limit-exceeded`](/code/api/errors/limit-exceeded); unanswered by its deadline, it ends `canceled`. |

## Example

**Ask**

```text
Authenticate the latest domain.
```

**API**

```bash
curl -X POST https://api.sb/routewise.dev/domains/domain_1/authenticate \
  -H "Authorization: Bearer $STARTUP_BUILDER_API_KEY"
```

```json
{
  "api": "https://api.sb/routewise.dev",
  "domain": {
    "$id": "https://api.sb/routewise.dev/domains/domain_1",
    "$type": "Domain",
    "hostname": "routewise.dev",
    "role": "canonical",
    "state": "verifying"
  },
  "action": {
    "$id": "https://api.sb/routewise.dev/actions/action_1",
    "operation": "Domain.authenticate",
    "status": "done"
  },
  "links": {
    "self": "https://api.sb/routewise.dev/actions/action_1"
  }
}
```

**SDK**

```ts
import { $ } from 'startup-builder'

const domain = await $.Domain.authenticate({ domain: 'domain_1' })
```

**CLI**

```bash
npx startup-builder do Domain.authenticate --json '{"domain":"domain_1"}'
```

**MCP**

```json
{
  "name": "do",
  "arguments": {
    "code": "return await $.Domain.authenticate({ domain: 'domain_1' })"
  }
}
```

Next: [`Mailbox.create`](/business/nouns/mailbox/create) (in `guide:get-email-at-my-domain`).

Guides that call it: [Get email at my domain](/products/site/domains/get-email-at-my-domain), [Send email from my domain](/start/guides/send-email-from-my-domain).