Email Validator
Validate email address format
Enter one address per line; surrounding whitespace is trimmed. This checks syntax only, with no DNS or MX lookup and no mailbox-existence or delivery check. Validate again after changing input or options.
Domains are lowercased by default, while the part before @ keeps its case. Deduplication compares normalized valid addresses; invalid rows are always retained. Local-part case may distinguish mailboxes, so confirm the receiving system’s rules before lowercasing it. The single-label option is for internal-name syntax checks.
Addresses are processed in this page’s memory, are not saved to browser storage, and are not sent to analytics. Copying places the selected list on your system clipboard.
Validation results
Enter addresses and click Validate emails to see the results.
Supported syntax and limits
Supports unquoted ASCII local parts, including + tags and valid characters such as apostrophes. The local part is limited to 64 characters, with no leading, trailing, or consecutive dots. The complete address is limited to 254 characters. Each domain label is limited to 63 letters, digits, or interior hyphens. Valid means that these rules pass.
Unicode addresses, quoted local parts, display names, comments, and bracketed IP domain literals are not supported. Internationalized domains must first be converted to ASCII Punycode; this tool only checks the resulting label syntax, not the conversion or domain existence. Some unsupported forms may be valid in other email systems.
The full guide also includes pitfalls, worked examples, snippets, FAQs, and related tools for checking results or troubleshooting.
About this tool
Check one email address per line and see a specific reason for each format failure. This checker supports unquoted ASCII local parts and ASCII DNS-style domain names. It checks dot placement, label boundaries and address lengths; it does not contact mail servers, query MX records, or confirm an inbox exists. Domain case is normalized, while the local part before @ is preserved by default. Optional deduplication uses that normalized address. Changing the input or options clears previous results. Email input is not saved to browser storage or included in this tool’s analytics.
Failure Clinic (Common Pitfalls)
A passing address still bounces
Cause: Syntax alone does not show whether a domain or inbox accepts mail.
Fix: Use the receiving system’s verification flow; do not interpret this local check as proof of deliverability.
Scenario Recipes
Check domain-case duplicates without merging local parts
Goal: Clean a small import sample while preserving potentially distinct recipients.
- Paste [email protected], [email protected], [email protected] and [email protected] on separate lines.
- Keep deduplication enabled and preserve local-part case. Run validation.
- The first two addresses are duplicates; lowercase alice remains separate. The last address fails because it has consecutive local-part dots.
Result: Two passing addresses, one failing address, and one removed duplicate. Copy only the list you intend to use.
Production Snippets
Four-row input sample
text
[email protected]
[email protected]
[email protected]
[email protected]Frequently Asked Questions
Does valid mean that the mailbox exists?
No. It means the address matches this checker’s supported syntax. Domain registration, MX records, recipient status and delivery acceptance are not checked.
Which addresses are outside the supported syntax?
Quoted local parts, comments, domain-literal IP addresses, Unicode domain names and non-ASCII local parts are not supported. An already encoded ASCII Punycode label can pass syntax checks, but its encoding, registration and mail setup are not verified.
Why preserve the text before @?
Mail domains are case-insensitive, while local-part handling belongs to the destination mail system. Preserving its case avoids silently merging [email protected] and [email protected].
Can I check or copy a list?
Paste one address per line, run validation, then copy the passing or failing list. Passing addresses can be deduplicated using normalized domain case and preserved local-part case; failing rows remain visible for correction.
Why is [email protected] rejected?
An unquoted local part cannot begin or end with a dot, or contain consecutive dots. The checker also rejects DNS labels that begin or end with a hyphen.
Are email lists stored or sent to a server?
Validation is local and this tool does not persist email input or send it in analytics events. Copying writes the selected list to your device clipboard.
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