Does this email address exist?
Checked without sending anything — and when the answer can't be known, we say so instead of guessing.
How it works
- The way the address is written gets checked — length, characters, structure of the domain. A malformed address can't be delivered by any server: the verdict is immediate and certain.
- The domain must declare a mail server — we look for its MX records, and failing that its address, which acts as the server. With neither, that domain cannot receive any message at all.
- An SMTP probe asks whether the recipient is accepted — we announce the sender (MAIL FROM), ask for two recipients (RCPT TO): a made-up address first, yours second. Then we hang up. The DATA command, the one that delivers a message, is never sent.
- The verdict accounts for doubt — if the made-up address is accepted, the domain accepts everything and nothing can be concluded. We show that, rather than picking an answer at random.
Use cases
- An address dictated over the phone or read off a piece of paper — confirm it exists before sending an important document, rather than waiting for a bounce that may never come.
- A contact who has gone quiet — find out whether their mailbox was deleted or whether it's them keeping silent.
- A suspicious sign-up on a form — check whether the address entered leads anywhere before creating an account.
- Before migrating a mailbox — make sure the destination address is really accepted by its new server.
- Diagnosing a bounce — work out whether the rejection comes from the address itself, from the domain, or from a server refusing every connection.
What this tool doesn't do
- It never sends a message: the probe stops before delivery. The owner of the address receives nothing.
- It can't conclude anything on a catch-all domain, which accepts every address. We detect it and say so: that's a limit of the protocol, not a fixable shortcoming.
- It checks one address at a time, five per quarter hour from the same IP address. An SMTP probe that pushes too hard gets the server running it blocklisted: the limit protects the tool itself.
- It doesn't tell you whether the mailbox is read, whether it's full, or whether its owner is still reachable: a server can happily accept mail for an address abandoned years ago.
- It is not a substitute for a real send on addresses judged to exist: a spam filter or a quota can still reject an actual message later.
- When the result is uncertain it shows "we can't tell" along with the exact reason. That's deliberate: a false certainty does more harm than no answer.
Frequently asked questions
How can you check an address without sending an email? +
By opening the beginning of an SMTP conversation with the domain's mail server: we announce a sender (MAIL FROM), ask whether the recipient is accepted (RCPT TO), and stop there. The DATA command, the one that actually transmits a message, is never sent. The recipient receives nothing and sees nothing.
What is a catch-all domain, and why does it change everything? +
A catch-all domain accepts mail for any address, whether it exists or not. On such a domain, "recipient accepted" proves nothing. We detect it by asking for a made-up address first: if that one is accepted, we answer "we can't tell" instead of selling you a false certainty.
Why is the result sometimes "we can't tell"? +
Because sometimes that's the only true answer: catch-all domain, temporary rejection (greylisting), unreachable server, session cut short, or a server that refuses our connection before the address is even mentioned. In all those cases we show the exact reason. A tool that always answers "valid" or "invalid" is simply guessing.
Can I check a whole list of addresses? +
Not with this tool: it checks one address at a time, with a limit of 5 checks per quarter hour from the same IP address. That isn't a commercial restriction but a technical one: an SMTP probe that pushes too hard gets the server running it blocklisted — ours — which would make the tool useless for everyone.
Is the address owner notified? +
No message reaches them, since nothing is delivered. The connection does show up in the logs of the domain's mail server, like any delivery attempt — unavoidable as soon as you query a server at all.
Why do some providers seem to accept everything? +
Several large providers deliberately accept every recipient at RCPT TO and sort things out after delivery, precisely to stop people enumerating their mailboxes. We detect them as catch-all and decline to conclude. It's frustrating, and it's honest.
What should I do if the verdict is "does not exist"? +
Check what you typed first: a wrong domain or two swapped letters is enough. If the address was given to you by its owner, ask them to confirm: a deleted mailbox, a former employee or an expired alias all produce the same hard rejection from the server.