# warm

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

> Warm ramps a new Mailbox from a few sends a day to its cap over two to four weeks.

Warm ramps a new [Mailbox](/business/nouns/mailbox) from a few sends a day to its cap over two to four weeks.

## Inputs
| Input | Type | Required | Description |
| --- | --- | --- | --- |
| `mailbox` | [Mailbox](/business/nouns/mailbox) | Yes | The new Mailbox. |
| `cap` | `integer` | Yes | The daily sends it ramps to. |

## Outputs
| Output | Type | Required | Description |
| --- | --- | --- | --- |
| `mailbox` | [Mailbox](/business/nouns/mailbox) | Yes | The Mailbox, warming. |

## Effects
- Emits [`Mailbox.warmed`](/business/events/Mailbox.warmed).
- Performed by the [Customer Lead](/agents/customer/customer-lead).
- Two-way: it runs at once, in the `try`, `send` and `do` modes.
- Raises the daily cap on a schedule while the spam rate stays under 0.1 percent.

## 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. | [Mailbox.warm](/business/nouns/mailbox/warm) |

## 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
Warm my mailbox.
```

**API**

```bash
curl -X POST https://api.sb/ledgerlark.com/mailboxes/mailbox_1/warm \
  -H "Authorization: Bearer $STARTUP_BUILDER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"cap":1}'
```

```json
{
  "api": "https://api.sb/ledgerlark.com",
  "mailbox": {
    "$id": "https://api.sb/ledgerlark.com/mailboxes/mailbox_1",
    "$type": "Mailbox",
    "medium": "email",
    "address": "priya@ledgerlark.com",
    "stream": "transactional"
  },
  "action": {
    "$id": "https://api.sb/ledgerlark.com/actions/action_1",
    "operation": "Mailbox.warm",
    "status": "done"
  },
  "links": {
    "self": "https://api.sb/ledgerlark.com/actions/action_1"
  }
}
```

**SDK**

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

const mailbox = await $.Mailbox.warm({ mailbox: 'mailbox_1', cap: 1 })
```

**CLI**

```bash
npx startup-builder do Mailbox.warm --json '{"mailbox":"mailbox_1","cap":1}'
```

**MCP**

```json
{
  "name": "do",
  "arguments": {
    "code": "return await $.Mailbox.warm({ mailbox: 'mailbox_1', cap: 1 })"
  }
}
```