# E-mail list cleaner: dedupe and check syntax

> Upload a CSV or paste up to 50,000 e-mail addresses: fix case and spacing, check syntax, remove duplicates, flag role and free-mail addresses. In your browser.

Canonical: https://mobilevalidate.com/tools/email-list-cleaner · Last updated: 2026-11-07

Upload a CSV or TXT file, or paste a list of e-mail addresses. The cleaner trims spaces, removes "mailto:" and display names, lower-cases the domain, checks each address's syntax, removes duplicates and flags role addresses (info@, sales@) and free-mail domains, with a suggestion for typos such as gmial.com. Download the clean CSV and the removed rows. Your list never leaves your browser.

Use the tool: https://mobilevalidate.com/tools/email-list-cleaner (interactive; needs a browser with JavaScript).

**Privacy:** Runs entirely in your browser. Nothing you type, paste or upload is sent to MobileValidate or anyone else, and nothing is stored. The page counts one anonymous "tool used" event per visit (no numbers, no text), and sends nothing at all when your browser asks not to be tracked.

## How it works

The file is read on your device. The cleaner detects the delimiter and the e-mail column (a header such as email or e-mail, or else the first column with an @); you can change the column before cleaning.

Each address is tidied first: spaces trimmed, a "mailto:" or a display name (Ann Lee <ann@example.org>) removed, the domain lower-cased. The part before the @ keeps its case, because mail systems may treat it as case-sensitive; duplicates are compared ignoring case, and the first occurrence is kept.

Syntax uses the same rules as our [e-mail checker](https://mobilevalidate.com/tools/email-checker): 64 characters before the @, a valid domain name after it, 254 in total, and no quoted names or IP addresses. Role addresses, free-mail domains and likely typos are flagged in the clean file, not removed: you decide what to do with them.

What it does not do: look up the domain's mail servers, spot disposable inboxes or confirm that a mailbox exists. Those need a server. The [e-mail checker](https://mobilevalidate.com/tools/email-checker) checks one address's domain and the disposable list; the [e-mail verification check](https://mobilevalidate.com/services/email-verification) answers whether the mailbox exists, for a whole list as a bulk job.

## Verify the cleaned list as a bulk job

Find out which mailboxes exist and which domains are disposable before you send. Upload the clean CSV as a bulk job and see the estimate before it runs; unknown answers are free.

- [Start free (10 free real checks)](https://mobilevalidate.com/request-access?service=email.valid)
- [How bulk jobs work](https://mobilevalidate.com/docs/bulk-jobs)
- [E-mail verification](https://mobilevalidate.com/services/email-verification)

## Related

- [Check if an e-mail mailbox exists](https://mobilevalidate.com/services/email-verification.md)
- [E-mail verification: the complete 2026 guide](https://mobilevalidate.com/blog/email-verification-guide.md)
- [Role-based e-mail addresses: accept, flag or block?](https://mobilevalidate.com/blog/role-based-email-addresses.md)
- [Free e-mail checker](https://mobilevalidate.com/tools/email-checker.md)
- [Bulk jobs](https://mobilevalidate.com/docs/bulk-jobs.md)

## Frequently asked questions

### How do I remove duplicate e-mail addresses from a list?

Tidy first, then compare ignoring case. The same address often appears as ANN@Example.com, ann@example.com and "Ann <ann@example.com>"; a plain text comparison counts those as three. The cleaner normalises each row and keeps the first occurrence of each address.

### Does a clean list mean the addresses work?

No. Cleaning removes addresses that cannot exist and copies of the same address. A well-formed address can still have a domain with no mail servers, be a disposable inbox or point to a mailbox that was closed. Our [e-mail verification check](https://mobilevalidate.com/services/email-verification) tells you whether the mailbox exists, and you pay only for conclusive answers.

### Why are disposable addresses not flagged here?

The disposable-domain list has about 9,000 entries and changes every week, so we keep it on our server instead of sending it to every visitor's browser. Check single addresses with the free [e-mail checker](https://mobilevalidate.com/tools/email-checker); a bulk verification job flags disposable domains for the whole list.

### Should I delete role addresses like info@ or sales@?

Not by default. A role address belongs to a team, which is normal for business contacts and invoices. Flag it where one person must own the account, such as a free trial or a login. See [role-based e-mail addresses](https://mobilevalidate.com/blog/role-based-email-addresses).

### What file formats can I upload?

CSV and TXT files up to 50,000 rows and 10 MB, or pasted text. Comma, semicolon, tab and pipe delimiters are detected automatically, with or without a header row. The clean CSV keeps your other columns.

### Is my list uploaded?

No. The file is read and processed in your browser, and the downloads are created on your device. Nothing is sent to MobileValidate or anyone else, and nothing is stored.