# `provider_unavailable`: the verification provider itself could not answer

The partner infrastructure that runs the mailbox handshake was unreachable, returned an error, or was held off by Spaw's circuit breaker. The lookup was answered from the free signals.

- Appears in: `smtp_reason`
- Billing: Billed by the verdict it produced: a deliverable answer with smtp_checked false is 1 credit. The settling re-checks are free.

After repeated provider failures Spaw stops sending probes for a few minutes and answers every mailbox check as unverified, so a provider incident never turns into a queue of slow requests. Such answers are never cached: the next lookup probes again as soon as the provider recovers.

smtp_checked is false and mailbox_exists is null; the verdict comes from syntax, DNS, the open lists and the domain signals.

**What to do.** Retry later, or pass callback_url so the settled verdict is pushed to you. If you see it across many lookups, quote a request_id to support@spaw.co.

```json
{
    "deliverable": "deliverable",
    "smtp_checked": false,
    "smtp_reason": "provider_unavailable",
    "mailbox_exists": null
}
```

Reference: https://spaw.co/docs/reasons/provider_unavailable