Online Tool Store
E-Mail Validator
Validate email address syntax individually or in bulk, with a plain-language reason for anything invalid. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Checks syntax only — can't confirm a mailbox actually exists without sending an email.
How it works
- Paste one or more email addresses, one per line.
- Each one is checked against standard email syntax rules.
- See which are valid and why any invalid ones failed.
FAQ
Does this confirm the email address actually exists?
No — it checks syntax only (correct format, valid characters, one @ sign, a domain with a dot). Confirming a mailbox actually receives mail requires either sending a real email or an SMTP-level check, which needs a server and can't be done from a browser.
What counts as invalid syntax here?
Missing or multiple @ signs, no domain or a domain without a dot, invalid characters, or a local/domain part exceeding the length limits the email standard defines (64 and 255 characters respectively).
Can I check a list of emails at once?
Yes — paste one email per line and every line is checked and reported individually.
Is my data uploaded anywhere?
No — validation happens entirely in your browser. Nothing is sent to a server.
How we compare
| Feature | Online Tool Store | Spreadsheet regex formula | Full SMTP verification services |
|---|---|---|---|
| Explains why each one failed | ✓ | Pass/fail only | ✓ |
| No account or credits needed | ✓ | ✓ | Usually paid per lookup |
For a quick syntax sanity check on a list before an import or a send, this is faster and free compared to paid mailbox-verification services.