Email Format Validator - Check Email Syntax Online
Email Format Validator
Check Email Syntax and See Exactly Why It Fails
Enter an email and click Validate
Understanding Email Address Syntax
Form Validation Logic
Test edge cases for a sign-up form's email regex before shipping it to production.
Debugging Rejected Signups
Understand exactly why a user's email address was rejected by a form or import script.
Cleaning Bulk Data
Spot-check individual rows from a CSV import that are flagged as invalid email addresses.
Local Processing
The address you test never leaves your browser — validation runs entirely client-side.
Syntax, Not Deliverability
This tool checks whether an email address is syntactically well-formed — correct use of "@", valid characters, a properly structured domain — not whether the mailbox actually exists or can receive mail. A syntactically valid address can still bounce, and there's no way to confirm deliverability without actually attempting to send (or using a dedicated verification service). Treat this as a first-pass sanity check, not a guarantee.
Key Takeaways
- Specific Failure Reasons: Get a clear list of exactly which rule(s) an invalid address violates.
- Syntax Only: A valid result means well-formed syntax, not a confirmed deliverable mailbox.
- Client-Side Only: All validation happens locally in your browser — no data is ever sent to a server.