Catch-all domain checker
A catch-all domain answers "yes, deliver it" to every address you ask about, including ones that cannot possibly exist. That single behaviour is responsible for most of the false positives in email validation.
Free, no signup, no daily limit. We do not store what you check here.
How the false positive happens
A validator connects to the receiving server and asks whether a mailbox exists. The server answers 250, meaning yes. The validator reports "valid" and bills you. But if that server answers 250 for every address, its answer carried no information at all - and when you send the campaign, the message hard-bounces.
The control probe
The fix is not a better probe, it is a second one. Ask the server about an address you know cannot exist, such as a long random string on the same domain. If it accepts that too, the server tells you nothing about the real address, and the only defensible verdict is "unknown". Our API returns exactly that, and charges nothing for it.
What to do with a catch-all address
Do not delete it and do not treat it as confirmed. Segment it. Send to catch-all addresses in a separate, smaller batch so that if they bounce, the damage to your sending reputation is contained rather than spread across your main campaign.
Questions
Why do domains do this?
Convenience, mostly. It means mail to a mistyped address still arrives. Large consumer providers and many small business domains are configured this way.
Does catch-all mean the address is fake?
No. It means the server will not tell you either way. The address may be perfectly real.
What share of a typical B2B list is catch-all?
It varies widely by industry, but it is common enough that any validator claiming near-total certainty on a B2B list is not being straight with you.
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When you need more than a free tool
This page answers what can be determined offline and from public DNS. The API adds live carrier and mailbox verification, a calibrated confidence score, and the full evidence trail behind every verdict.
Credits never expire. Inconclusive verdicts are never billed. Cancel in one call. See pricing or read the docs.