How the free email verifier works
Every check runs four tests, usually in about a second. First we check the syntax, because an address with a typo or a missing piece can never be valid. Then we look up the domain's mail servers (the MX records) to confirm it can receive mail at all. Next we open a connection to that mail server and ask whether the specific mailbox exists, without ever delivering a message. Finally, when a server says yes, we ask it about a made-up address too: if that is accepted as well, the domain accepts everything and the result is catch-all.
What each result means
- Valid: the mailbox exists and accepts mail. Safe to send.
- Invalid: the mailbox does not exist or cannot receive mail. Remove it before you send.
- Catch-all: the domain accepts any address, so the exact mailbox cannot be confirmed. Send with caution.
- Disposable: a throwaway address from a temporary-inbox service. Almost never worth keeping.
- Unknown: the mail server would not give a clear answer this time. We tell you honestly rather than guess.
Why verify before you send
Every email that bounces is a small mark against your sender reputation. Send to enough dead addresses and Gmail, Outlook, and Yahoo start routing your mail to spam, even for the people who do want to hear from you. Verifying first keeps your bounce rate low and your inbox placement high. If you want the full picture, read our complete guide to email verification or see how we stack up in the best email verification services comparison.
Frequently asked questions
Is the email verifier really free?
Yes. You can run real checks right here with no account. When you sign up you get 100 free verifications with no credit card, which is enough to clean a small list or test the engine on your own data.
Do you send an email to verify the address?
No. The check is silent. We talk to the receiving mail server the same way a sending server would, up to the point of asking whether the mailbox exists, then stop before any message is delivered. The person being checked never gets an email.
How accurate is it?
Every address gets a live check against its own mail server, not a guess from syntax or a stale database. Results are most certain on Gmail, Outlook, and Yahoo; the hard cases are catch-all domains, where no check can confirm the mailbox: we detect them with a live probe and label them catch-all instead of guessing. No verifier is perfect on every address, so when a mailbox genuinely cannot be confirmed we say so and do not charge for it.
What does 'catch-all' mean?
A catch-all domain accepts mail to any address, even ones that do not exist, so a single check cannot prove one specific mailbox is real. When a server accepts your address, we also ask it about a made-up one. If that is accepted too, the result is catch-all: risky, clearly labelled, and free.
Can I verify a whole list at once?
Yes. Upload a CSV or Excel file and we verify the entire list, checking duplicates only once, and you download it back with a result on every row, ready to filter. Create a free account to run a bulk job.
Clean your whole list, free to start
Create an account for 100 free verifications. No credit card. Upload a CSV or Excel file and get every address back with its result.
No credit card · live mailbox check · real-time