Paste or upload a list of email addresses — one per line, or separated by commas — and get a full breakdown of which are valid, which are duplicates, and which use disposable domains, with a one-click export of the clean list.
Once you click Check list, the tool splits your input on line breaks, commas and semicolons, then runs each entry through the same format validation used in the single-address checker. It additionally tracks addresses it has already seen, so the second and later occurrences of the same address (case-insensitively) are flagged as duplicates rather than counted as separately valid.
Every address is bucketed into one of four categories — valid, invalid, disposable-domain, or duplicate — and you get a count for each alongside a full row-by-row table so you can see exactly which entries need attention before you import a list into a CRM or email platform.
Sending to a list full of malformed addresses or duplicates hurts more than it helps: invalid addresses generate hard bounces, which most email service providers use as a signal that damages your sender reputation, and duplicates waste sends and skew your open-rate numbers. Running a list through this checker before an import is a quick way to catch obvious problems — though for large lists intended for cold outreach, pairing this with the Deliverability Tester on a sample of addresses gives a more complete picture, since only a live MX lookup can catch a domain with no working mail servers at all.
For lists larger than a few thousand rows sourced from an old CRM export or a purchased list, it's also worth spot-checking a random sample with the Email Deliverability Tester, since format validity alone won't catch a batch of addresses at a domain that stopped accepting mail entirely. Beyond pre-send hygiene, this tool is also useful on the receiving end — if you're importing a contact export from an old system, a trade show scan list, or a CRM migration, running it through this checker first surfaces obviously broken entries and internal duplicates before they clutter your database or skew your reporting.
There's no hard cap built into the tool — it runs in your browser, so practical limits depend on your device's memory. Lists of a few thousand addresses process almost instantly.
Yes. Use the upload button to load a .txt or .csv file — the tool reads any email-shaped text in the file regardless of extra columns or commas.
The exported 'valid addresses only' list only includes the first occurrence of each address, so duplicates are automatically removed from the clean export.
No — like the single Email Validator, this checks format, known disposable domains and duplication, not live mailbox status. Use the Email Deliverability Tester for a domain-level MX check.
No. Parsing and checking both happen locally in JavaScript in your browser tab — the list is never sent over the network, whether you paste it or upload a file.