Email Address Validator
The email validator checks addresses against practical syntax rules and explains what is wrong with each one that fails — a missing @, a doubled dot, a domain with no top-level part, an over-long local part. It checks a whole list at once and can show only the valid or only the invalid results.
Email addresses (one per line)
Results
Your result will appear here.
Not sure where to start? Use Load example.
Results update automatically and are calculated on your device. Nothing you type is sent to a server.
Runs in your browser. Processing happens entirely in your browser. Nothing you enter is sent to Delimiter.live.
How to use the Email Address Validator
- Paste one address per line.
- Read the result column — valid addresses are marked, and each failure explains what is wrong.
- Switch the filter to show only the invalid ones when cleaning a list.
- Copy the filtered result.
Example
Input
ada@example.com broken@
Output
ada@example.com Valid broken@ Nothing after the @
Common use cases
- Cleaning a mailing list before importing it, so bad rows do not fail the import.
- Finding the malformed addresses in a form export.
- Checking a list of addresses collected by an extractor.
- Explaining to a colleague why a particular address was rejected.
Limitations and things to watch for
- This checks syntax only. It cannot tell you whether an address exists, whether the mailbox accepts mail, or whether the domain has an MX record — only sending mail proves that.
- The rules applied are deliberately practical rather than RFC 5322 complete. The full grammar permits quoted local parts, comments and nested constructs that no real mail system delivers to, and accepting them would make the tool less useful.
- Internationalised addresses with non-ASCII local parts are not accepted, because support for them across mail providers remains inconsistent.
Frequently asked questions
Does a valid result mean the address works?
No. It means the address is correctly formed. The mailbox may not exist, the domain may not accept mail, and the address may have been abandoned. Only sending a message and getting a response proves deliverability.
Why is a technically legal address marked invalid?
RFC 5322 permits constructs — quoted local parts, embedded comments, bare IP-address domains — that essentially no mail provider accepts. The checks here match what works in practice, which is the more useful answer when cleaning a list.
Does it check the domain exists?
No, and it cannot: that needs a DNS lookup, which a browser cannot perform. Use the DNS Lookup tool and query the MX records for the domain if you need to confirm it accepts mail.
Are the addresses uploaded?
No. Validation runs entirely in your browser, which matters because a mailing list is personal data.