# Catch-all domain

A catch-all domain is one whose mail server accepts mail addressed to every recipient, whether or not that mailbox exists.

Date: 2026-09-10

A catch-all domain is one whose mail server accepts mail addressed to every recipient, whether or not that mailbox exists. It is also called accept-all. The server answers `250 OK` at the `RCPT TO` step for any name, then sorts the mail out afterwards — delivering what matches a real mailbox, forwarding the rest, or dropping it.

## What Spaw answers

The field is `catch_all`. When it is true the handshake proved that the domain receives mail and proved nothing about the mailbox, so the verdict is `risky` with the reason [`catch_all`](/docs/reasons/catch_all) and the risk score carries +30. `mailbox_exists` stays null, because no honest answer can be given.

Spaw does not report a catch-all address as deliverable, ever. The verdict names what was established rather than what is likely.

## What it does not mean

Catch-all is a property of the domain, not of the address. Most catch-all domains are ordinary businesses whose server was configured that way on purpose, and mail to a real person there arrives normally. It is a reason to treat the address as unconfirmed, not a reason to discard it.

Where a probe ran and left `mailbox_exists` null, `mailbox_confidence` carries a recomputable 0–100 estimate that this particular mailbox exists, built from the domain's mail authentication, its registration age, the shape of the local part and, once a domain has five or more reported delivery outcomes, the share of them that bounced. It is a published heuristic, not a probe, and the page that lists its inputs says so.

Reference: https://spaw.co/glossary/catch-all-domain