Verify your email list before you send: clean it instantly in your browser, then check addresses against live mail servers. Free, with no signup.
Paste your email list
Files are parsed in your browser, so your list is never uploaded.
Clean your whole list instantly: deduped, syntax-checked and flagged, entirely in your browser. Then verify 10 addresses a day free against live mail servers.
Paste or upload your list
Paste up to 10,000 emails, or upload a .csv or .txt file. It's parsed in your browser and nothing is uploaded.
Clean it instantly
We dedupe, lowercase and syntax-check every address, and flag role accounts and free providers.
Verify addresses
Check your first 10 addresses a day against live mail servers, free, valid, invalid or catch-all.
Export and send
Download or copy the cleaned list, then verify the rest in bulk inside Emailchaser.
Email list cleaning is the fastest deliverability win there is. This tool deduplicates your list, lowercases and syntax-checks every address, and flags role accounts (info@, sales@, support@) and free personal providers (Gmail, Yahoo, Outlook), instantly, for lists up to 10,000 rows.
Everything happens locally: the file you pick is read with your browser's own FileReader, and your list is never uploaded to any server. When cleaning is done, copy the results or download them as a .txt file with one click.
Paid bulk email verifier software checks every mailbox on your list by talking to the receiving mail server (an SMTP check). This free bulk email verifier runs the exact same check (the same engine that powers Emailchaser's product) on up to 10 addresses per day, so you can gauge the quality of a list before committing to anything.
When you're ready to verify the whole list, Emailchaser verifies thousands of addresses in one click, automatically, before every campaign sends, so a stale list never touches your bounce rate.
A clean email list is the difference between the inbox and the spam folder. Every send to a dead address counts as a bounce, and once your bounce rate creeps past 2-3%, providers like Google and Microsoft start filtering everything you send.
Addresses also go stale fast (people change jobs constantly) so cleaning isn't a one-off. Run your list through this tool before every campaign: dedupe it, drop the invalid syntax, decide what to do with role and free-provider addresses, and verify what remains.
Each address you verify triggers a short live conversation with the receiving mail server, the same SMTP handshake a real send would start. A valid result means the server accepted the recipient (a 250 response) and the mailbox can receive mail, so it's safe to send. An invalid result means the server rejected the address (a 550-style response): that mailbox doesn't exist and will hard-bounce, so pull it off the list before you send.
A catch-all (accept-all) result is the tricky one. The domain is configured to accept mail for every possible address, so the server says yes to any recipient and can't confirm that one specific inbox is real. Microsoft 365 tenants and security gateways like Proofpoint and Mimecast are common sources of catch-all responses. Some of those addresses are perfectly deliverable and some are dead, so treat a catch-all as a calculated risk, not a guarantee. An unknown result usually means the server greylisted the check or timed out without a definitive answer, wait a while and re-run those addresses, and many resolve to valid on the second pass.
Your bounce rate is the share of messages that get rejected instead of delivered: bounces divided by total sent. Send a campaign to 1,000 addresses, have 38 come back undelivered, and you're at 3.8%, already past the point where Google and Microsoft start throttling you. For cold outreach the goal is to keep hard bounces close to zero, which in practice means verifying before you send rather than letting the mailbox providers discover the dead addresses for you.
It helps to separate the two kinds of bounce. A hard bounce is permanent (the mailbox doesn't exist or the domain can't receive mail) and it's what damages your sender reputation; these are exactly the addresses verification catches ahead of time. A soft bounce is temporary (a full mailbox, an oversized message, or a server that's briefly down) and usually clears on a later send. Track the hard-bounce number specifically, and if you're sending from a freshly warmed domain, aim tighter than 2% while your reputation is still forming. Google Postmaster Tools and Microsoft SNDS both let you watch how the providers see your domain.
Email data decays quickly (industry estimates put B2B contact rot at roughly 30% a year as people change jobs and companies fold) so list hygiene is a routine, not a one-time fix. Clean and re-verify a list before every campaign, and treat any purchased, scraped, or months-old list as unverified until you've run it through again. Just as important, keep a permanent suppression list of every hard bounce so a dead address never sneaks back into a future send.
A practical pass looks like this: dedupe the list (this tool does it inline, or use the dedicated Remove Duplicates tool for a raw paste), drop anything that fails the syntax check, decide what to do with the flagged role and free-provider addresses, verify what's left, and suppress every invalid result. Hold catch-all addresses in a lower-volume segment so a batch of uncertain addresses can't spike your bounce rate on its own. And if a whole domain looks questionable, an MX Lookup confirms it can receive mail at all before you spend verifications on it. When a contact you actually want is the one that bounced, our email finder will look their current work address up again from their name and company domain.
How do I verify an email list?
Paste your list (or upload a .csv or .txt file) into the tool above. It instantly cleans the whole list (deduplicating, lowercasing and syntax-checking every address) then verifies your first addresses against the live mail server, one at a time, so you know which mailboxes can actually receive email. To verify thousands at once, sign up for Emailchaser and every address is verified in bulk before your campaign sends.
Is my email list uploaded anywhere?
No. List cleaning runs 100% in your browser, files are read locally with your browser's FileReader, and the list never leaves your device. Only the individual addresses you explicitly choose to verify are checked, one at a time, against our verification service.
How many email addresses can I verify for free?
Cleaning is unlimited and instant, for lists up to 10,000 rows. Live SMTP verification is free for up to 10 addresses per day. If you need your whole list verified, sign up for Emailchaser, it verifies thousands of addresses in one click before every campaign.
What do valid, invalid and catch-all mean?
Valid means the mailbox exists and can receive email, so it's safe to send. Invalid means the address doesn't exist and will bounce, remove it before sending. Catch-all means the domain accepts mail for every address, so the specific inbox can't be confirmed; treat these as risky. Unknown means the mail server didn't give a definitive answer in time.
Why remove role and free-provider addresses before cold outreach?
Role accounts like info@ or sales@ are shared inboxes. They rarely reply, are watched by spam filters, and are more likely to report you. Free-provider addresses (Gmail, Yahoo, etc.) are usually personal accounts, not the business decision-maker you're targeting in B2B outreach. Flagging both lets you focus your sends on real, individual work addresses.
What bounce rate is safe for cold email?
Keep your bounce rate under 2-3%. Above that, mailbox providers like Google and Microsoft start treating your domain as a spam risk, which pushes even your good emails to the spam folder. Verifying your list before every send is the most reliable way to stay under that threshold.
Does verifying an email address send a message to that person?
No. The verifier opens a connection to the recipient's mail server and asks whether the mailbox exists (the RCPT TO step of the SMTP conversation) then disconnects before any message is transmitted. Nothing lands in the person's inbox, and they get no notification that their address was checked.
What is the difference between a hard bounce and a soft bounce?
A hard bounce is permanent: the address doesn't exist or the domain can't receive mail, so it will never be delivered and should be removed for good. A soft bounce is temporary (a full mailbox, an oversized message, or a server that's briefly unavailable) and often succeeds on a later attempt. Hard bounces are the ones that hurt your sender reputation, and they're exactly what verifying a list ahead of time prevents.
Should I send cold emails to catch-all addresses?
Cautiously. A catch-all domain accepts mail for every address, so the verifier can't confirm the specific inbox is real. Some will deliver and some will bounce. Instead of dropping them all or blasting them, put catch-all addresses in a smaller, separate segment so that if a chunk of them bounce, it doesn't push your overall bounce rate past the safe threshold.
Why does the verifier say unknown instead of valid or invalid?
Unknown means the mail server didn't give a definitive yes or no in time, usually because it greylisted the probe (a deliberate anti-spam delay) or the connection timed out. It's not the same as invalid, and the address may well be fine. Wait a little and re-check those specific addresses; many resolve to valid on a second pass.
How often should I clean and re-verify my email list?
Re-verify right before every campaign, and treat any list older than about 30 to 90 days as stale, since contacts change jobs constantly. Always clean bought or scraped lists before their first send, because you have no idea how old those addresses are. Keeping a running suppression list of past hard bounces means you never re-mail an address you've already proven is dead.
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