New Playbook: Cold Email Infrastructure Setup Guide

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Free catch-all email checker: find out if a domain accepts every address

Paste a domain or an email address. We ask its mail server about an address that cannot possibly exist and show you exactly what came back. If the server accepts that, the domain is catch-all and no verifier on earth can confirm a single mailbox on it. No signup. 5 free checks a day.

Try it

filter_drama Enter a domain or email above to test the mail server.

What a catch-all domain is

A catch-all domain, sometimes called an accept-all domain, is configured to accept mail sent to any address at that domain. Write to a colleague who left two years ago, or to a name you invented, and the server still says yes. Companies set this up so that a typo in an address does not bounce, and it is common on Google Workspace and Microsoft 365 setups where one mailbox catches everything unrouted.

For anyone verifying email, a catch-all is the one case an SMTP check cannot settle. The verifier asks the server whether a mailbox exists, and the server says yes to everything, so the answer carries no information. Honest verifiers report this as catch-all, risky or unknown. Less honest ones report it as valid, which is how a list that looked 98 percent clean produces a wave of bounces a week after the send.

This tool proves the behaviour rather than asserting it. It generates a random address that nobody could own, asks the mail server about it, and shows you the raw answer. Accepted means catch-all. Rejected means the server answers honestly and a verification result on that domain can be trusted.

What this checker does

science

Probes with an impossible address

A random local part nobody owns, so an acceptance can only mean the server accepts everything.

dns

Reads the MX record

Shows which mail server answered and which provider runs it, because catch-all behaviour is a server setting.

mark_email_read

Checks your address too

Paste a full address and it is verified alongside the probe, with a plain note when the result cannot be trusted.

visibility

Shows the raw answer

The server's own words, not a score. You can see why the verdict is what it is.

Why it matters

~1 in 5

Share of B2B domains that behave as catch-all in a typical prospecting list.

0

Verifiers that can confirm a single mailbox on a catch-all domain, including this one.

< 2%

Bounce rate the big inbox providers tolerate before they start throttling you.

Pricing

Free

$0

100 verified lookups per day, forever. No card.

Monthly

$9.99/mo

75,000 credits per cycle.

Lifetime

$249 once

1,000,000 credits, lifetime pool.

Frequently asked questions

Is a catch-all address safe to email? expand_more
It is a judgement call rather than a yes or no. The address may be a real person, or it may be a typo that the server quietly swallows. Many teams send to catch-all addresses in a separate, smaller batch, watch the bounce and reply rates, and keep them out of the main campaign until they have evidence. What you should not do is treat a catch-all as verified, because no verification has actually happened.
Why does my verifier say valid when this says catch-all? expand_more
Because a plain SMTP check on a catch-all domain gets a yes for every address, and some tools report that yes as valid. Mailsfinder returns Unknown in the API and risky with a catch-all flag in the app for exactly this reason, and ZeroBounce and Emailable attach a score instead. The difference is not accuracy, it is honesty about what the server actually told them.
Can I find out which addresses are real on a catch-all domain? expand_more
Not through SMTP, because the server will not tell you. The signals that remain are indirect: whether the address appears in public sources, whether the pattern matches the company's known format, and whether the person still works there. Mailsfinder uses the pattern and its own data to raise confidence, but it will not claim certainty it does not have.
Do catch-all domains hurt my sender reputation? expand_more
Only if the address turns out to be dead and the server bounces it later, which does happen with delayed bounces. The safer read is that catch-all addresses carry unknown risk, so they belong in a segment you can watch rather than in a 50,000 address blast.
How is this different from the email verifier? expand_more
The verifier answers "does this mailbox exist". This tool answers "can that question be answered at all on this domain". Run this first when a whole company's addresses come back risky, and you will know in a second whether it is the domain rather than your list.

Related reading

Tool

Free email verifier

Check one address with a real SMTP handshake, catch-all flagged.

 Money page

Catch-all email verification

How Mailsfinder charges for and handles catch-all domains at scale.

 Listicle

Catch-all verifiers compared

Which tools claim to resolve catch-all domains, and what they actually do.

 Tool

Disposable email checker

The other address type that passes a syntax check and wastes a send.

Flag every catch-all in one pass

Upload a list and Mailsfinder marks the catch-all domains separately, so you decide what to do with them instead of finding out at bounce time.

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