Instant check
Verify an Email Address
Instant check against live mail servers. Free, no signup, and nothing is sent to the address you enter.
5 free checks per day, counted per IP address and shared across every checker on this site.
Step by step
What happens when you verify.
The address you typed above goes through five stages. Each one can settle the question on its own, and most addresses never reach the last.
01
Syntax
The address is parsed against the rules for what an address may contain. This catches the typo cases: a missing @, a trailing comma pasted from a spreadsheet, a space in the middle, a domain ending in a stray full stop. It costs nothing and rules out a surprising share of what arrives in real lists.
02
Domain
The domain to the right of the @ is looked up in DNS. If nothing resolves, the address cannot receive mail from anyone and the check ends here. This is where addresses at misspelled domains fail, and where you catch a domain that has lapsed since the contact was collected.
03
Mail servers
A domain resolving is not the same as a domain accepting mail. This stage reads the MX records to find which servers handle mail for it. A domain with no MX records may host a website perfectly well and still be incapable of receiving a message.
04
Mailbox
A conversation is opened with the mail server that handles the domain, and the server is asked about the specific mailbox. No message is ever sent. Most addresses are settled here, and this is the stage that distinguishes a real person from a plausible guess at one.
05
Catch-all resolution
Some servers answer yes to every mailbox regardless of whether it exists. Stage four cannot settle those, so a second pass re-tests the address with deeper SMTP-level verification and waterfall routing. This is the stage most validators skip, and it is why an address here more often returns a verdict than an unknown.
Why check first
The cost of guessing.
The obvious way to find out whether an address works is to email it and see what comes back. That answer arrives, but it is expensive. A message to a mailbox that does not exist produces a hard bounce, and hard bounces are the clearest signal a mailbox provider has that a sender does not know who they are writing to.
Providers track that ratio per sending domain. A domain that bounces a small fraction of its volume is treated as careful. One that bounces several percent starts landing in spam folders, and the damage is not limited to the campaign that caused it: it follows the domain, and it takes weeks of clean sending to undo. For a business running outreach from a domain it also uses for customer email, that is a genuinely bad trade.
There is a quieter failure mode as well. Addresses that were abandoned years ago are sometimes reactivated by the provider as spam traps, and mail to them does not bounce at all. It is accepted, silently, and recorded as evidence that the sender is working from a stale list. Because nothing comes back, a sender can keep hitting the same traps for months without noticing, which is why old contact data deserves a check even when it looks plausible.
Checking first avoids the whole exchange. Nothing is delivered, nobody is contacted, and the answer arrives in under a second. That is the entire argument for verification, and it is why the check is worth doing even for a single address you are fairly confident about.
In practice
Common reasons to check one address.
Checking a lead before you reach out
You have a name and an address from a data provider, a conference list or a colleague. One bounce on a cold domain is a real cost, and the address has never been tested. Checking it takes a few seconds and tells you whether the first message in a sequence will land or damage the domain sending it.
Validating an address someone gave you
A signup, a form submission, an address written on a business card and typed in by hand. Typos in this direction are common and silent: the person believes they gave you a working address, and you believe you have one, until the first message disappears. Verifying at the point of entry closes that gap.
Testing your own address or a new mailbox
You have set up a new sending domain or a fresh mailbox and want to confirm it is reachable from the outside before you route anything through it. This checks it the way a sender would, from outside your own network, without you emailing yourself and hoping.
Beyond one address
When one check is not enough.
Checking addresses one at a time works until it does not. Two situations outgrow it quickly, and both have a different answer.
A list before a campaign
Addresses decay. People change jobs, mailboxes close, and a list that was clean six months ago is not clean now. Running the file before each send is the habit that keeps bounce rates low. Upload a CSV of up to a million rows, and the email column is detected for you.
Real time, inside your product
A signup form that accepts a mistyped address has already lost the user, because the confirmation email will never arrive. The single-verification endpoint answers in a few hundred milliseconds, which is fast enough to sit inline in a form submission.
Both run the same engine as the checker above, including the catch-all resolution pass. More detail on how that works is on the features page.
FAQ
Questions about verifying an address.
Can you verify an email address without sending an email?
Yes, and that is the point of the exercise. The check opens a conversation with the mail server that handles the domain and asks whether it will accept mail for that specific mailbox, then stops before any message is transmitted. The person on the other end sees nothing. Sending a test message to find out would tell you the same thing while announcing yourself to a stranger and risking a bounce on your own domain.
What is a catch-all domain, and why does it complicate things?
A catch-all domain is configured to accept mail for every possible address at it, whether or not that mailbox exists. Ask such a server about anything@company.com and it says yes. That makes the ordinary mailbox check useless there, which is why most validators return catch-all or unknown and stop. Catch-alls are common on larger organisations, so on business lists they cover roughly a quarter of addresses.
How fast is a single verification?
Usually under a second. Most addresses are settled by the mailbox stage, which is a short exchange with a mail server. Addresses that need the second pass take longer because more work is being done, and a small number of servers are slow to answer by design. If a check feels slow, the address is almost always one of the interesting ones.
What does a risky verdict mean for the address I just checked?
It means the address resolves but carries something you should weigh before sending. It may be a role account such as support@ or billing@, which reaches a shared inbox rather than a person. It may be a disposable address from a throwaway provider. Or it may sit on a catch-all domain where the second pass reached a conclusion without high confidence. None of these are hard failures, and none are the same as a confirmed mailbox.
Is there an API for verifying addresses programmatically?
Yes. A REST API with key-based auth covers single addresses and bulk submissions of up to 10,000 per call, returns predictable JSON, and delivers HMAC-signed webhooks for jobs that run asynchronously. Teams typically wire the single endpoint into a signup form to reject bad addresses at the point of entry, and use the bulk endpoint for scheduled list cleaning. The full reference is in the API documentation.
Does verifying addresses actually protect sender reputation?
It protects the input to it. Mailbox providers judge a sending domain partly on how often it tries to deliver to addresses that do not exist, and a high hard-bounce rate is read as a signal that the sender does not know who they are mailing. Removing invalid addresses before a send keeps that rate low. Verification cannot fix poor content, bad targeting or a sudden spike in volume, which are the other ways reputation is lost.
One address, or a million.
The checker above is free forever. When the list gets bigger, 100 free credits are waiting and no card is required.
Looking for the tool rather than the explanation? The free email verifier page covers what the free tier includes and how it compares to other free checkers.