Bulk Email Format Validator
Check a list of email address formats and duplicates without uploading addresses.
One value per line, up to 10,000 lines and 2 MB. Original line numbers are preserved. Blank lines are skipped. Input is held in this tab only.
Check your list
Ready. Checks run on this device; this tool does not upload your input.
What the result means
Uses a practical ASCII address format check with domain-label checks and length limits. Quoted local parts and internationalized addresses may need specialist review. It does not check DNS, mailbox existence, delivery, consent or whether an address can receive mail.
Duplicate checks use exact trimmed text and remain case-sensitive. No emails are sent and no remote URLs are fetched. CSV exports escape spreadsheet formula prefixes.
Continue your workflow
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