Catch-all checker

Find out if a domain is catch-all

Enter a domain to test whether its mail server accepts mail for every possible address. The tool opens one SMTP conversation with the domain's mail server and asks whether a random, non-existent mailbox is accepted.

Test a domain for catch-all

Domain or email address

This opens one SMTP conversation with the domain's mail server and asks whether a random mailbox is accepted. Many networks block outbound port 25, so a single check can be inconclusive.

Catch-all domains need smarter verification

On a catch-all domain, the server accepts everything, so SMTP alone cannot tell a real mailbox from a typo. Verifly combines multiple signals and flags catch-all addresses so you can decide how to send.

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Catch-all reports by domain

Pre-built reports showing MX configuration and a live catch-all probe for popular domains.

What is a catch-all domain?

A catch-all (or accept-all) domain is configured to accept mail for any address, even ones that do not exist. A message to a typo or a guessed name is accepted at the gateway instead of being rejected.

Many companies run catch-all to avoid losing mail to small typos, but it makes verification harder.

Why catch-all matters for verification

On a catch-all domain, an SMTP accept does not prove a mailbox exists. The server says yes to everything, so a verifier cannot use acceptance alone to confirm an address.

This is why catch-all addresses are usually labeled separately. Verifly flags them so you can decide how aggressively to send rather than treating them as confirmed.

How the catch-all probe works

The checker looks up the domain's highest-priority MX host, opens an SMTP conversation with it, and issues a RCPT TO for a random address that almost certainly does not exist, such as vf-9f3a7c1@yourdomain. A normal server rejects that unknown mailbox with a 550. A catch-all server accepts it with a 250, because it is configured to accept everything.

That single answer is the whole test: if a random, guaranteed-nonexistent mailbox is accepted, the domain accepts all addresses. No real mail is sent and no message body is delivered; the probe stops before DATA.

Why catch-all makes verification uncertain

On a normal domain, an SMTP accept is a reliable signal a mailbox exists. On a catch-all domain that signal disappears: the server says yes to ceo@, sales@, and pure gibberish alike. So a verifier cannot promote a catch-all address to "valid" on acceptance alone, and honest tools label it as its own accept-all or unknown category.

Behind that gateway the address may still bounce later, or route to a human who filters aggressively. Catch-all addresses are best treated as a middle tier: riskier than a confirmed mailbox, but far better than a hard-invalid or disposable address.

Interpreting the result and its limits

Three outcomes are possible. Catch-all means the random mailbox was accepted. Not catch-all means it was rejected, so acceptance of a real address on that domain is meaningful. Inconclusive usually means outbound port 25 is blocked, the MX greylisted the probe, or the server deferred; this is common and does not indicate a problem with the domain.

Catch-all status is a policy, not a permanent trait: an admin can toggle it. For sending decisions across a whole list, pair this with disposable and role checks, or verify in bulk with the Verifly API at https://verifly.email/api/v1, whose GET /verify response includes a dedicated catch-all flag. See how catch-all fits alongside role and disposable signals in the email risk checker.

Frequently asked questions

What is a catch-all (accept-all) domain?

It is a domain whose mail server accepts messages for every possible address, even ones that were never created. Companies use it so mail sent to small typos is not lost, but it means an SMTP accept no longer proves a specific mailbox exists.

Does sending to a catch-all domain guarantee a bounce?

No. Many catch-all addresses reach a real person or a monitored inbox and deliver fine. Others silently discard or bounce later at a second layer. Catch-all simply means acceptance at the gateway is not proof of a real mailbox, so treat these addresses as medium risk.

Why did the checker return "inconclusive"?

The most common cause is that outbound port 25 is blocked on the network running the probe, so the SMTP handshake cannot complete. Greylisting, rate limiting, or a temporary server deferral can also produce an inconclusive result. It reflects the connection, not a flaw in the domain.

Can a catch-all domain stop being catch-all?

Yes. Accept-all is a configuration an administrator sets, so it can change at any time. A domain that tests catch-all today may reject unknown mailboxes next week, which is why it is worth rechecking before a large send.

Should I email addresses on catch-all domains?

It depends on your risk tolerance. For cold outreach, sending to catch-all addresses raises your bounce risk, so many senders exclude or throttle them. For warm, opted-in contacts the risk is much lower. Segmenting catch-all addresses separately gives you that control.

How do I test catch-all across a whole list?

This tool checks one domain at a time. To flag catch-all across thousands of addresses, use the Verifly API with a vf_ Bearer key: GET /verify?email= returns a catch-all flag along with disposable, role, and SMTP results.

Embed this catch-all checker on your site

Drop this snippet into any page to add a live, self-contained checker. It links back to Verifly, costs nothing, and needs no API key.

<iframe
  src="https://verifly.email/tools/embed/catch-all-checker"
  width="100%" height="680"
  style="border:0;border-radius:12px;max-width:760px"
  title="Catch-All Checker by Verifly"
  loading="lazy"></iframe>
<p style="font:13px sans-serif">
  Free <a href="https://verifly.email/tools/catch-all-checker">Catch-All Checker</a> by
  <a href="https://verifly.email">Verifly email verification</a>
</p>

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