Free Email Validator
Clean email lists, detect duplicates and validate supported address syntax locally. Import CSV or TXT and export clear results with mailbox status marked unknown.
Clean an email list
10,000 addresses, 2 MB maximum. Domain structure only; DNS and mailboxes are not checked.
Validation results
No addresses checked.
Valid syntax does not prove deliverability. Duplicates are flagged case-insensitively.
How to use the Email Validator
- Paste addresses separated by lines, commas or semicolons, or import a UTF-8 CSV/TXT file.
- Validate to trim whitespace, flag duplicates and check supported syntax.
- Review invalid and unsupported addresses, then export the results as CSV.
Practical example
A list containing person@example.com twice and broken@@example.com reports one valid supported address, one duplicate and one invalid syntax result.
What inputs and outputs are supported?
| Input and limits | Pasted lines or CSV/TXT; 2 MB; 10,000 addresses; CSV email/address column or first column |
|---|---|
| Output | Valid supported syntax, invalid syntax, unsupported syntax, duplicates and CSV |
Limits, assumptions and troubleshooting
The supported subset is unquoted ASCII local parts with valid dot placement and DNS-style domain labels; Unicode domains are converted to IDNA ASCII by the browser. Quoted local parts, domain literals and internationalized local parts are labeled unsupported for review. Duplicate detection is case-insensitive for list cleanup, although standards allow case-sensitive local parts. Domain checks here cover structure only: no DNS/MX lookup is performed. Mailbox existence and deliverability are always unknown. A syntactically valid address can still bounce.
Is my data private?
Input processing and output creation run on your device. This tool does not upload inputs, filenames or outputs, and analytics are disabled. The page loads normal website styles and fonts. Reset releases the current work; download a copy before leaving. This tool does not persist your input in browser storage.
Provided by Toolcross. Read our privacy policy or contact us with a reproducible issue. Updated .
Frequently asked questions
Does Valid mean the mailbox exists?
No. Valid means the supported syntax passed. Domain DNS, mailbox existence, spam policy and deliverability are not verified.
Are addresses uploaded?
No. List parsing, duplicate detection and CSV export happen locally. No email or DNS verification request is sent.