Free Tool
Free Catch-All Email Checker
A catch-all email checker tells you whether a domain is configured to accept mail for every possible address, also called an accept-all domain. Because a catch-all server accepts everything, an SMTP probe cannot prove a specific mailbox exists, so we flag the address risky rather than valid. 10 checks per day, no signup, no card.
Need to run this on every signup or clean an email list? Use the API
Paste an address above. Or try one of the examples below.
What is a catch-all email address?
A catch-all email address belongs to a domain configured to accept mail for every possible mailbox at that domain. The real user's address and a random string of characters both get the same acceptance from the server. Because the server accepts everything, an SMTP probe cannot tell you whether the specific mailbox actually exists. That is why a catch-all is flagged risky rather than valid: it is deliverable at the server but unconfirmed at the mailbox. Anyone who returns valid for a catch-all address is guessing.
What does the catch-all email checker return?
Enter any email address and you get the catch-all verdict, the honest deliverability status, and the domain's mail servers in one result, so you know exactly what you are dealing with before you send.
Catch-all verdict (yes or no)
We test whether the domain accepts mail for an address that should not exist. If a random, never-used address is accepted, the domain is a catch-all and we flag it. This is the headline result.
Honest deliverability status
Alongside the catch-all flag you get a status: safe, risky, invalid, or unknown. For a catch-all domain the status is risky, because no SMTP check can confirm a specific mailbox behind an accept-all server. Deliverable at the server, unconfirmed at the mailbox.
MX records and mail servers
We look up the domain's MX records and show them. A catch-all still needs working mail servers to receive anything, so this confirms the domain can accept mail at all, separate from whether your specific mailbox exists.
Why do catch-all addresses matter?
A catch-all hides the one thing you want to know: does this mailbox exist? The domain accepts everything, so a clean SMTP response means nothing on its own. Treating a catch-all as deliverable is where lists rot and bounce rates climb.
Bounce risk
A catch-all server accepts your mail at the SMTP layer, then can still silently drop it or bounce it after delivery. Addresses that looked fine on a probe turn into hard bounces in a real send. That is the gap between accepted and delivered, and a catch-all is exactly where it lives.
List hygiene
Catch-all domains let typos and made-up addresses sail through. Every address at the domain is accepted, so a list collected from a catch-all carries unknown weight. Flagging those addresses risky instead of valid keeps the rot out of your clean segment. See the disposable email database for more signals to layer in.
Lead quality
A form fill on a catch-all domain is not a confirmed contact. The mailbox might be real, or it might be a guess. Knowing the domain is accept-all lets sales treat it as unverified rather than burning time on an address that may never have existed.
Why you cannot trust a valid claim
Any tool that returns valid for a catch-all address is guessing, because the server accepts every address identically. We flag it risky and tell you why. An honest risk flag is more useful than a confident wrong answer.
How does catch-all detection work?
Catch-all detection is an SMTP behavior test, not a lookup. We ask the domain's mail server how it responds to an address that should not exist, and read the answer. Understanding the steps tells you why a catch-all is honestly flagged risky rather than valid.
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. Working MX records are the prerequisite for the SMTP step.
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, which is the definition of a catch-all.
Why the verdict is risky
Because a catch-all accepts the random address and the real address identically, the SMTP response cannot distinguish a real mailbox from a fake one. There is no honest way to confirm the specific mailbox exists, so we flag the address risky rather than label it valid.
A catch-all verdict is one input, not a verdict on the person. Pair it with disposable detection, role-based detection, and domain age, and decide per use case how much risk a catch-all address carries before you accept or send to it. The email verification API returns all signals in one call.
What does catch-all detection cost at scale?
This tool is free for 10 checks a day. To run catch-all detection on every signup or across a list, the same check ships in the email verification API. 100 validations a month free, no card required.
Pay for what you check. Cancel anytime. Overage is billed through Stripe at $0.001 per validation regardless of volume.
What counts as a validation? One request to the validation endpoint is one validation. Failed calls (4xx from your side) do not count.
Frequently asked questions
A catch-all email belongs to a domain set to accept mail for every possible address at that domain. The real mailbox and a random string both get accepted by the server. Because the server accepts everything, you cannot tell from an SMTP check whether one specific mailbox actually exists.
