Catch-all verification

Catch-all verification that never charges you for a guess

Some company mail servers accept every address, real or not, so no mail-server check can prove a specific mailbox exists there. We test for that on every accepting server, tell you plainly which addresses sit on catch-all domains, and charge nothing for them.

Check your list free How it works
  • Probed on every accepting server
  • Labelled catch_all, never hidden in unknown
  • Always free

How we detect a catch-all domain

  1. We ask the receiving mail server whether your address exists, the way a sending server would, and stop before any message is sent.
  2. If the server says yes, we open a second conversation with the same server and ask about a random made-up address that cannot belong to anyone.
  3. If the server rejects the made-up address, it was telling the truth about yours: your address is confirmed and returned as ok.
  4. If it accepts the made-up address too, it accepts everything: the result is catch_all, quality risky, catchAll: true, and it costs nothing.

The answer for a domain is remembered for a few hours, so a list with hundreds of addresses at one company does not hammer that company's mail server. Free mailbox providers such as Gmail and Outlook.com reject unknown addresses, so they are never tested this way.

Why it matters

A basic check sees "250 OK" from a catch-all server and reports the address as valid. You send, and some of those "valid" addresses bounce, because the server accepted the message and then threw it away or bounced it later. Testing a made-up address on the same server is what separates a real yes from a server that says yes to everything.

Why catch-all results are free

  • No answer, no charge

    A catch-all result means the mailbox could not be confirmed either way. Charging for that would be charging for a guess.

  • Everywhere, automatically

    The same rule applies to single checks, batches of 30, bulk jobs of 500,000 and every integration. Unknown and error results are free too.

  • Clearly labelled

    Catch-all addresses come back as catch_all with their own flag, not mixed into unknown, so you can segment them.

  • Scored in the risky band

    Their 0-100 risk score sits between 30 and 69, nudged up for role addresses or likely typos, so it never reads as a confirmed mailbox.

What to do with catch-all addresses

  • Keep them separate. Send to confirmed (good) addresses first and to catch-all addresses as their own segment.
  • Start small. Send to a slice, watch hard bounces, and only widen if they stay low.
  • Use what you already know. An address that has opened or replied before is real, whatever its domain does.
  • Be wary of role addresses. info@ or sales@ on a catch-all domain is the least likely to be read by a person.
  • Remove what bounces. A hard bounce from a catch-all domain is the confirmation the server would not give.

For a longer walk-through with examples, read catch-all emails explained.

Catch-all verification FAQ

What is a catch-all email address?

An address on a domain whose mail server accepts mail for any address at all, real or not. The server says yes to everything, so asking it whether a mailbox exists tells you nothing.

Can any verifier confirm an address on a catch-all domain?

Not from the mail server: a true catch-all gives the same answer for a real person and a made-up name. Tools that grade individual catch-all addresses are estimating from other signals, not confirming. We would rather tell you plainly that the address is unconfirmed than sell you a guess as an answer.

Do catch-all results cost credits?

No. A catch-all result confirms nothing about the mailbox, so it is free, in single checks, batches, bulk jobs and integrations alike.

Why is a Gmail or Outlook.com address never catch-all?

Free mailbox providers reject addresses that do not exist, so we do not run the catch-all test on them: their answer about the real address is already definite.

How do I know the domain was really catch-all?

We only call a domain catch-all when its server accepts a random made-up address we tested right after yours. If the server rejects the made-up address, your address is confirmed as a real mailbox and returned as ok.

Should I email catch-all addresses?

Often yes, carefully. They are frequently real people at companies. Send to them separately from confirmed addresses, in smaller batches, watch the bounces, and drop any that bounce.

Go further

See how much of your list sits on catch-all domains

Free credits on sign-up. No card. You only pay for definite answers.

Start free