# Sprint 2.3 — DNS and health checks

**Status:** Done

## Backend

- `POST /api/mailboxes/:id/dns-check` — SPF/DKIM/DMARC via existing `dns-check` lib
- `GET /api/mailboxes/provider-presets` — SMTP/IMAP defaults for wizard and add-mailbox flow

## Dashboard

- Mailbox detail: DNS check card with pass/warn/fail badges
- Campaign wizard step 4: compliance checklist preview
- Mailbox add flow supports provider presets

## Verification

```bash
curl -X POST http://localhost:3000/api/mailboxes/{id}/dns-check \
  -H "x-api-key: $API_KEY"
```

Or use **Run DNS Check** on mailbox detail in the dashboard.