Check and clean a list of email addresses
A mailing list is personal data, which is exactly why it should not be pasted into a website that checks it on a server. This one checks it in your browser and does not have a server to send it to.
- Runs entirely in your browser
- Works offline
- No upload
- No sign-up
- No watermark
Loading the tool…
How it works
- Paste the addresses, one per line or straight from a spreadsheet column.
- Read the findings per address; typos and disposable domains are the ones worth acting on.
- Copy the clean list back into your mailing tool, or download the CSV.
Why nothing is uploaded
Every operation on this page is done by code running inside your browser tab, using the same engine that renders web pages. The file is read from disk into your tab’s memory, transformed there, and written back out as a download. It is never sent anywhere — not to us, not to a third party.
Verify it yourself
- Open your browser’s developer tools (F12) and select the Network tab.
- Load your file and run the tool.
- The only requests you will see fetch the tool’s own code — and, for a few heavy tools, their open-source engine from a public CDN — plus one small page-view ping to loreatec.jp (page address and title, nothing more). None of them carry your file.
Frequently asked questions
Why does it not check whether the address exists?
Because a browser cannot do it, and even a server can barely do it. Verifying a mailbox means opening an SMTP conversation with the receiving server, which needs a server of your own, and many providers answer “yes” to everything to defeat exactly that. What is worth checking is the domain’s MX record, which is a DNS question — the e-mail DNS checker on this site does it.
What is a role account and why flag it?
info@, support@, sales@ and the like go to a shared mailbox, not a person. Writing to one is normal business; adding one to a marketing list is how you collect spam complaints, because nobody there subscribed and several people can press the button.
Why normalise Gmail addresses?
Gmail ignores dots in the local part and treats anything after a + as the same mailbox, so t.aro+news@gmail.com and taro@gmail.com are one person. That matters for deduplication and for suppression lists. Send to the address as it was given to you, though — the normalised form is for matching, not for sending.
How complete is the disposable-domain list?
It is a well-known open list of a few thousand domains and it can never be complete — new ones appear constantly. A domain missing from it proves nothing. Treat a hit as a signal, not a rule; some people use a forwarding service for perfectly ordinary reasons.
Where does my list go?
Nowhere. It stays in this tab, no DNS lookup is made, and nothing is uploaded. Close the tab and it is gone.