Email normalizer & validator
Trim whitespace, lowercase the domain and collapse dots or + aliases according to provider rules to get the canonical form; includes an alias-rule table for 15 common providers, RFC 5322 (simplified) syntax checks with RFC 5321 length limits, and batch processing. Everything runs locally, with no DNS lookups.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
One address per line (multiple lines are processed as a batch; blank lines and lines starting with # are ignored).
Result
firstlast@gmail.com firstlast@gmail.com a.b@outlook.com base@yahoo.com user.name@example.com bad-address ✗
5146Everything runs locally: no DNS/MX lookups, and no check whether the mailbox actually exists. ASCII only: international domains must be Punycode-encoded (xn--).
Batch result
| Line | Input | Canonical form | Status |
|---|---|---|---|
| 1 | First.Last+news@gmail.com | firstlast@gmail.com | Valid |
| 2 | first.last@googlemail.com | firstlast@gmail.com | Valid |
| 3 | A.B+c@outlook.com | a.b@outlook.com | Valid |
| 4 | base-tag@yahoo.com | base@yahoo.com | Valid |
| 5 | <User.Name@Example.COM> | user.name@example.com | Valid |
| 6 | bad-address | — | Invalid · Missing @ |
Alias rules of common providers
| Provider | Equivalent domains | + alias | - alias | Dots ignored | Notes |
|---|---|---|---|---|---|
| Gmail / Google Workspace | gmail.com, googlemail.com | Yes | No | Yes | Ignores dots and case; text after + is an alias; googlemail.com equals gmail.com. |
| Outlook / Hotmail / Live | outlook.com, hotmail.com, live.com, msn.com | Yes | No | No | Supports + aliases; dots are significant and cannot be added or dropped. |
| Yahoo Mail | yahoo.com, ymail.com, rocketmail.com, yahoo.co.jp | Yes | Yes | No | Supports both + and - aliases; dots are significant. |
| iCloud Mail | icloud.com, me.com, mac.com | Yes | No | No | Supports + aliases; dots are significant. |
| Proton Mail | protonmail.com, proton.me, pm.me | Yes | No | No | Supports + aliases; pm.me is the short domain for paid users. |
| Fastmail | fastmail.com, fastmail.fm | Yes | No | No | Supports user+folder@ and user@folder.fastmail.com subdomain addressing. |
| Zoho Mail | zoho.com, zohomail.com | Yes | No | No | Supports + aliases; business accounts may use domain aliases. |
| Yandex Mail | yandex.ru, yandex.com, ya.ru | Yes | No | No | Supports + aliases; ya.ru belongs to the same service as yandex.ru. |
| Mail.ru | mail.ru, inbox.ru, list.ru, bk.ru | Yes | No | No | Supports + aliases; inbox.ru, list.ru and bk.ru belong to the same service. |
| QQ Mail | qq.com, foxmail.com | No | No | No | No + alias; aliases must be configured as separate accounts in the settings. |
| NetEase 163 Mail | 163.com | No | No | No | No + alias; use the alias-account feature instead. |
| NetEase 126 / yeah.net | 126.com, yeah.net | No | No | No | No + alias; yeah.net belongs to the same provider as 126.com. |
| AOL Mail | aol.com | Yes | No | No | Supports + aliases; dots are significant. |
| Tuta (formerly Tutanota) | tuta.com, tutanota.com, tuta.io | Yes | No | No | Supports + aliases; the legacy tutanota.com domain still works. |
| GMX | gmx.com, gmx.net, gmx.de | No | No | No | No + alias; aliases must be configured in the account settings. |
What this tool does
- Deduplicate a user list: alice.bob+news@googlemail.com, AliceBob@gmail.com and alice.bob@gmail.com collapse to one canonical address, so nobody gets the same email twice.
- Clean data before importing: strip surrounding whitespace, angle brackets, a mailto: prefix and trailing punctuation, and lower-case the domain.
- Validate addresses against RFC 5322 (simplified) for local-part characters, dot placement and domain labels, plus the RFC 5321 length limits of 64 / 255 / 254 bytes.
- Look up whether a provider supports + aliases and dot-equivalence: a built-in offline rule table covers 15 common providers.
Example
Input
alice.bob+news@googlemail.com
Output
Cleaned (deliverable form): alice.bob+news@googlemail.com Normalised (for deduplication): alicebob@gmail.com Detected provider: Gmail / Google Workspace Alias tag: news (separator +) Changes: alias removed, dots removed, domain alias folded (case and whitespace were already normalised, so they are not listed)
Gmail ignores dots, treats text after + as an alias and considers googlemail.com equal to gmail.com, so all three spellings collapse to one canonical address; with outlook.com the dots would be preserved.
Frequently asked questions
Can I send mail to the normalised address?
No — send to the cleaned form, which only trims whitespace and lower-cases the domain and is still a valid address. The normalised form exists for deduplication, treating AliceBob@gmail.com as the same person as alice.bob+news@googlemail.com; sending to it can fail at some providers.
Does it do DNS or SMTP verification?
No. It only checks syntax and length: no MX lookup and no connection to the recipient server, so "valid" means the format is legal, not that the mailbox exists. Everything is computed locally.
Which providers get dot or alias folding?
The built-in table covers 15 providers: Gmail / Google Workspace ignores dots and supports + aliases; Outlook / Hotmail / Live, iCloud, Proton, Fastmail, Zoho, Yandex, Mail.ru, AOL and Tuta support + aliases but treat dots as significant; Yahoo additionally supports - aliases; QQ Mail, NetEase 163 / 126 and GMX support no + alias at all.
Does it handle international or Chinese addresses?
No, validation is ASCII-only. Anything non-ASCII raises a non-ascii error — convert the domain to its Punycode xn-- form first; the local part cannot be non-ASCII under RFC 5322 either, except for the rare quoted form.
What are the batch limits?
One address per line, blank lines and lines starting with # are skipped, up to 5000 lines. The result reports valid and invalid counts plus the number of unique addresses, and duplicates are listed in first-seen order so you can find the offending records.
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