# `no_connect`: no mail server accepted a connection on port 25

The MX hosts resolved but none of them accepted a connection: a firewall, a server that is down, or an MX that points at something other than a mail server.

- 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.

Different from mx_unresolvable, where the hosts do not even resolve. Here DNS is fine and the machines refuse or drop the connection. The mailbox stays unverified and the free signals decide the verdict.

**What to do.** Retry later. If no_connect persists for days on a business domain, its mail is probably broken and the addresses should be treated as risky.

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

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