Remove duplicate emails from a list
Paste your list, or open a CSV, and get it back with every repeat removed. You'll see what repeated and how often, and the list never leaves your browser.
One address per line, or separated by commas, semicolons or tabs. The list stays in this tab.
The short version
- The first spelling of each address is kept, in the original order, so your list still lines up with its source.
- Case is ignored by default, because the large mailbox providers ignore it too.
- Turn on plus-tag folding before a send, so ada+news@ and ada@ get one message between them.
- Uploading to ZapBounce? You can skip this step: duplicates are never billed there.
How duplicates are matched
Your paste is split on new lines, commas, semicolons and tabs, and quotes around an entry are stripped. That handles a single CSV column, a copied spreadsheet range or a comma-separated line from a CRM export.
Each entry then gets a matching key. With case folding on, the key is the lowercased address. With plus-tag folding on, anything from a + up to the @ is dropped too. Two entries with the same key are duplicates, and the first one you pasted is the one kept.
| Entries | Default | With plus tags folded |
|---|---|---|
| ada@example.com, ADA@example.com | One address | One address |
| ada@example.com, ada+news@example.com | Two addresses | One address |
| ada@example.com, ada@example.co | Two addresses | Two addresses |
| "ada@example.com", ada@example.com | One address | One address |
Why duplicates cost more than a wasted send
A duplicate means one person gets your email twice. A second copy is an easy reason to hit report spam, and complaints weigh heavily with Gmail and Yahoo. Google asks bulk senders to keep complaints under 0.1%, and our complaint rate calculator shows where you stand.
Duplicates also inflate every per-address bill, starting with your ESP's contact count. ZapBounce checks and bills each address once per list, whatever the repeats, so the cost calculator takes duplicates out before it prices your list.
Merging lists from several sources? Dedupe first, then check the result with the email list quality score to see what else the merge brought in.
Questions people ask
How do I remove duplicate email addresses from a list?
Paste the list or open a .csv or .txt file above. The tool keeps the first copy of each address, removes the rest, and shows which addresses repeated and how often. Download the clean list as a CSV.
Are email addresses case-sensitive when removing duplicates?
The standard allows the part before the @ to be case-sensitive, but Gmail, Outlook, Yahoo and nearly every business mail server ignore case. That's why the tool treats Ada@Example.com and ada@example.com as one address by default. Untick the option to compare exactly.
Should I treat plus-addressed emails as duplicates?
Only for a sending list. ada+news@example.com and ada@example.com reach the same inbox on Gmail and Microsoft 365, so mailing both sends the person two copies. Tick the plus-tag option to fold them together.
Do email verifiers charge for duplicates?
ZapBounce never bills a duplicate. When you upload a list, each address is checked and billed once, however many times it appears, and unknown results are free too.
Clean list, next step: live addresses
ZapBounce checks each address over SMTP and closes before DATA, so nothing is sent. $5 for 1,000, and credits never expire.