Free tool

Catch-all email checker. See if a domain accepts any address.

Q: What is a catch-all email address?

A catch-all belongs to a domain that accepts mail for every possible mailbox. The real user's address and a random string of characters both get the same acceptance from the server, so an SMTP probe cannot tell you whether the specific mailbox exists.

Q: Why is a catch-all address usually risky?

Because the server's acceptance proves nothing about the individual mailbox, so calling it safe would be a guess. Risky means deliverable at the server, unconfirmed at the mailbox. When a second check confirms the mailbox, we return safe instead.

Q: Are catch-all domains bad?

No. Plenty of legitimate companies run accept-all so that misspelled addresses still reach someone. It does mean you cannot verify individual mailboxes there, and that bounce risk is higher than for a confirmed mailbox.

Q: Can I still email a catch-all address?

Yes, and it will usually arrive. Just do not treat it as a verified user, and watch the bounce rate if a large share of your list sits on catch-all domains.

Q: Does the catch-all flag come through the API?

Yes. Every validation response includes isCatchall, on every plan including the free tier. The status next to it is risky, or safe or invalid when a second check resolved the mailbox.

A catch-all email checker tells you whether a domain accepts mail for every possible address, also called an accept-all domain. SMTP cannot prove a mailbox exists behind a catch-all server, so the address is risky by default. For some catch-all domains a second check confirms or rules out the mailbox, and you get a definite safe or invalid. 10 checks per day, no signup, no card.

Need to run this on every signup or clean an email list? Use the API

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False positive rate<1%

Median responseSub-1s

Free here10 / day

With a free account100 / month

Check a domain for catch-all.

10 free checks a day, no signup and no card. Nothing is sent to the address you check.

Or try

Unconfirmed mailboxes

A catch-all server says yes to every address, so a typo and a real person get the same answer.

Hidden bounce risk

Mail to a catch-all can be accepted now, then dropped or bounced later, after it counts against you.

Lists that look cleaner than they are

Catch-all addresses pass a basic check and sit in your list as if someone had verified them.

How does catch-all detection work?

We test the domain with an address that should not exist.

MX lookup

First we resolve the domain's MX records to find its mail servers. No MX records means the domain cannot receive mail at all, which is a different answer from catch-all.

SMTP probe on a random address

We open an SMTP handshake and test how the server treats a random, never-issued address at the domain. We stop before any message is sent. If the server accepts that address, it accepts everything.

Risky, unless a second check resolves it

A catch-all accepts the random address and the real one in the same way, so SMTP cannot tell them apart. The address stays risky unless a second check, which does not use SMTP, confirms or rules out the mailbox.

What each result means.

Every answer, in plain English.

safe

The mailbox is confirmed. If the domain is catch-all, a second check proved this exact address exists, so you can treat it as verified.

risky

Usually a catch-all we could not resolve: the server accepts every address, so this mailbox is unconfirmed. Send, but do not treat it as verified.

invalid

The address cannot receive mail. A catch-all domain gets this verdict too when a second check rules the mailbox out.

unknown

The mail server did not answer clearly, so we cannot say if the domain accepts every address.

Three quick definitions.

What is a catch-all email address?

A catch-all email address belongs to a domain that accepts mail for every possible mailbox. The real user's address and a random string of characters both get the same acceptance from the server, so an SMTP probe cannot tell you whether the specific mailbox exists.

Accept-all and catch-all: the same thing?

Yes. Both names describe a domain configured to accept mail for any address at that domain. You will see accept-all in some verification tools and catch-all in others. Trueguard returns one flag for it either way.

When is a catch-all address safe?

When a second check confirms the mailbox. By default a catch-all address is risky, because the server's acceptance proves nothing about one mailbox. For some domains we can confirm or rule out the mailbox without SMTP, and then the verdict is a definite safe or invalid. The catch-all flag stays true either way.

When should you use the API instead of this page?

The API returns the same signals plus structured fields and 50,000 monthly validations on the paid plan. The free tier is 100 a month, no card.

One address, by hand

This page

A handful of leads from a CSV

This page, or the API with a 10-line script

Every signup, every form submit

Email validation API. Call it from your backend.

Hundreds of thousands a month

Email validation API, Standard plan

curl -X POST https://api.trueguard.io/v2/email/validation \
  -H "X-API-KEY: $YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email":"name@example.com"}'

Read the API documentation

Questions about catch-all domains.

Still stuck? Contact support or read the documentation.

What is a catch-all email address?

A catch-all belongs to a domain that accepts mail for every possible mailbox. The real user's address and a random string of characters both get the same acceptance from the server, so an SMTP probe cannot tell you whether the specific mailbox exists.

Why is a catch-all address usually risky?

Because the server's acceptance proves nothing about the individual mailbox, so calling it safe would be a guess. Risky means deliverable at the server, unconfirmed at the mailbox. When a second check confirms the mailbox, we return safe instead.

Are catch-all domains bad?

No. Plenty of legitimate companies run accept-all so that misspelled addresses still reach someone. It does mean you cannot verify individual mailboxes there, and that bounce risk is higher than for a confirmed mailbox.

Can I still email a catch-all address?

Yes, and it will usually arrive. Just do not treat it as a verified user, and watch the bounce rate if a large share of your list sits on catch-all domains.

Does the catch-all flag come through the API?

Yes. Every validation response includes isCatchall, on every plan including the free tier. The status next to it is risky, or safe or invalid when a second check resolved the mailbox.

Flag catch-all domains automatically.

The same check runs through our validation endpoint. 100 free a month, no card. Same accuracy, same response shape, ready to drop into your backend.

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