Duplicate Email Cleaner: Dedupe and Validate Lists
Paste an email list to remove duplicates, find invalid addresses, sort, and export a clean CSV or text list. Free, no sign-up.
Free with no sign-up. Everything runs in your browser: nothing is uploaded or stored.
Your email list
Paste a list to remove duplicates and find obvious mistakes.
How it works
- Paste addresses separated by new lines, commas, or semicolons.
- Each entry is trimmed; mailto prefixes, angle brackets, and trailing punctuation are removed.
- Duplicates are removed case-insensitively, keeping the first spelling of each address.
- Obvious syntax mistakes are listed separately so you can fix the source list.
- Copy the cleaned result as one-per-line text or as a CSV with an email header.
Why dedupe before you send
Duplicates inflate your send count and annoy the same person twice, which is how interested contacts become complaints. Bounces from malformed addresses do the rest of the damage: a high bounce rate is one of the fastest ways to lose sender reputation.
This is a syntax check, not a deliverability check: it never contacts a server, so it cannot confirm that a mailbox exists. For the wider setup, work through the deliverability checklist, and keep the count healthy with the benchmark calculator.
Frequently asked questions
What counts as an invalid address?
The checker flags entries missing an @ sign, a domain, or a dot in the domain, and entries containing spaces or other clearly invalid characters. It is a syntax check, not a deliverability check.
Does it verify that an address exists?
No. Verifying a mailbox requires a network check against the receiving server, which this browser tool deliberately does not do. It removes formatting mistakes and duplicates before you send.
Is the list uploaded?
No. Parsing and deduplication run in your browser; the addresses never leave your device.
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