# `mailbox_full`: the mailbox is over its storage quota

The server accepted the address but answered that the mailbox cannot take more mail right now. The account is real and may be read again once space is cleared.

- Appears in: `reason`, `smtp_reason`
- Verdict: risky
- Risk weight: +20
- Billing: 1 credit, like every deliverable or risky answer. Repeats of the same address are free for 7 days.

The handshake reached the recipient check and the server replied with a "mailbox full" class response (a 452 or 552). The mailbox exists, it just has no room, which is why the verdict is risky rather than undeliverable.

As a reason it sets the verdict. As an smtp_reason it explains a probe result on a lookup that another signal may already have settled; the same value appears in both fields for the same address.

**What to do.** Keep the address but hold the send and retry in a few days. For transactional mail that matters, use another channel meanwhile.

```json
{
    "email": "mia@acme.com",
    "deliverable": "risky",
    "reason": "mailbox_full",
    "smtp_reason": "mailbox_full",
    "mailbox_exists": true
}
```

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