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Email Validator

Processed Client Side

Check email addresses for correct syntax against the rules mail servers actually enforce, spot disposable inboxes, role accounts, duplicates and likely domain typos — then optionally confirm the domain can receive mail with an MX lookup.

Email addresses
emailLength: 176Lines: 8Size: 176 BytesCursor: 1:1
Validation report
2 invalid
8checked
6valid
2invalid
4to review
1disposable
2role
0duplicates
ada.lovelace@example.com
local: ada.lovelacedomain: example.comtld: com
grace+navy@gmail.com
Free provider
  • ! Uses a plus-address tag — many providers deliver it to the base mailbox
local: grace+navydomain: gmail.comtld: comnormalised: grace@gmail.com
admin@acme.io
Role account
  • ! "admin" is a role account — it reaches a team, not a person
local: admindomain: acme.iotld: io
support@mailinator.com
DisposableRole account
  • ! mailinator.com is a disposable/throwaway inbox provider
  • ! "support" is a role account — it reaches a team, not a person
local: supportdomain: mailinator.comtld: com
user@gmial.com
  • ! Did you mean user@gmail.com?
local: userdomain: gmial.comtld: com
bad@@example.com
  • ✕ Address contains more than one "@"
  • ✕ Local part contains an invalid character: "@"
no-at-sign.example
  • ✕ Missing "@" — an address needs a local part and a domain
first.last@sub.domain.co.uk
local: first.lastdomain: sub.domain.co.uktld: uk
Syntax checking runs entirely in your browser. The optional MX check sends only the domain name (never the address) to Cloudflare’s public DNS-over-HTTPS resolver.

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About Email Validator

This tool runs entirely in your browser. Whatever you paste is processed on your own device and is never uploaded, logged, or sent to any server.

The Email Validator checks whether an email address is actually well-formed, using the practical subset of RFC 5321/5322 that real mail servers enforce rather than the full grammar nobody implements. Paste one address or a whole list and it tells you which are valid, which are broken and exactly why, and which are technically valid but worth a second look — disposable inboxes, shared role mailboxes, duplicates hiding behind Gmail dots and plus-tags, and domains that look like a typo for a big provider. An optional MX lookup then confirms whether the domain has mail servers at all.

Key features

  • Validates the local part and the domain separately, with a specific reason for every failure instead of a bare "invalid"
  • Enforces the real length limits — 64 characters for the local part, 253 for the domain, 254 overall
  • Handles the awkward but legal forms: quoted local parts, plus-address tags, IP address literals, IDN and punycode (xn--) domains, and display names like Ada Lovelace <ada@example.com>
  • Flags disposable/throwaway inbox providers such as Mailinator, YOPmail, and 10MinuteMail
  • Flags role accounts (info@, support@, admin@, no-reply@) that reach a team rather than a person
  • Suggests the intended domain when an address is one or two edits away from a major provider — gmial.com, hotnail.com, outlok.com
  • Detects duplicates by normalised mailbox, so ada.lovelace+news@gmail.com and adalovelace@gmail.com are recognised as one inbox
  • Bulk mode — paste hundreds of addresses separated by newlines, commas, or semicolons and get a per-address report plus totals
  • Optional MX record check over DNS-over-HTTPS to confirm the domain can receive mail
  • Syntax checking runs entirely in your browser — addresses are never uploaded

How to use it

  1. Paste one address, or a whole list with one per line, into the left pane. Commas and semicolons split addresses too, and lines starting with # are ignored.
  2. Read the report on the right: green means valid syntax, amber means valid but worth reviewing, red means it will bounce.
  3. Turn on "Only show problems" to hide the addresses that passed cleanly and focus on the ones that need fixing.
  4. Click "Check MX" to look up mail servers for each distinct domain — a domain with no MX records cannot receive mail at all.
  5. Use "Copy valid only" to lift the clean, de-duplicated list straight into your import, CRM, or test fixture.

Tips & common mistakes

  • Syntax validity is not deliverability. An address can be perfectly formed and still bounce, which is why the MX check exists — it is the strongest signal you can get without actually sending mail.
  • A missing MX record is close to conclusive: with no mail servers published, the domain cannot accept email no matter how the address is spelled.
  • Treat the typo suggestions as prompts, not corrections. gmial.com is almost certainly a slip, but a legitimate domain can sit one character away from a big provider.
  • Role accounts are the leading cause of spam complaints on marketing lists, because nobody in particular signed up for them. Filtering them out usually improves deliverability more than anything else on this page.
  • Gmail ignores dots and everything after a "+" in the local part, so several different-looking addresses can be one mailbox. The duplicate check normalises for exactly that.
  • Beware of regexes copied from Stack Overflow that reject valid addresses: plus tags, apostrophes, long new TLDs, and IDN domains are all legal and all commonly rejected by hand-rolled patterns.
  • The addresses you paste never leave your browser. Only the domain names are sent, and only when you press Check MX.

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Frequently asked questions

9

Paste the address into the left pane and read the result on the right. The tool checks the local part and the domain against the rules mail servers actually enforce and tells you exactly what is wrong — a missing @, a double dot, an illegal character, an oversized local part, or a bad top-level domain — rather than just "invalid".

Yes. Paste as many as you like, one per line — commas and semicolons split addresses too, and lines starting with # are ignored. You get a per-address report plus totals for valid, invalid, disposable, role, and duplicate addresses, and a "Copy valid only" button that returns the clean de-duplicated list.

No. Syntax validation proves the address is well-formed, not that a mailbox is behind it. The only checks that go further are an MX lookup, which confirms the domain publishes mail servers at all, and actually sending a message. This tool does the first; nothing short of the second can prove a mailbox exists.

It queries the domain's MX records over Cloudflare's public DNS-over-HTTPS resolver. Only the domain name is sent — never the full address, and never the list. A domain with no MX records cannot receive email, which makes a missing MX record a strong bounce predictor. Syntax checking itself is entirely offline.

Warnings mark addresses that are syntactically fine but risky in practice: disposable inbox providers like Mailinator, role mailboxes like info@ or support@ that reach a team rather than a person, plus-address tags, duplicates of an address already in your list, and domains that look like a typo for a big provider.

The domain is compared against the major mailbox providers using edit distance. If it is one edit away — or two on a longer domain — you get a suggestion of the address you probably meant. Treat these as prompts rather than corrections: a legitimate domain can sit one character from a big provider.

Yes, on Gmail. Gmail ignores dots in the local part and everything after a "+", so both deliver to the same inbox. The validator normalises for this when checking duplicates, so the second one is flagged as a duplicate of the first even though the strings differ.

Yes. "quoted local"@example.com, user@[192.168.1.1], and internationalised or punycode (xn--) domains are all recognised as valid where the RFCs allow them. The first two get a warning because many real mail systems reject them despite being legal.

No. All syntax validation runs in JavaScript in your browser, so pasting a customer list here does not transmit it. The only network request the tool ever makes is the optional MX lookup, and that sends the domain name alone.