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Checkers · Validation tools

Email malformed checker

Check a list of email addresses for malformed syntax and common formatting mistakes — missing symbols, stray characters, and typo'd domains.

Runs in your browser No signup Free forever Format check only — no mailbox ping

Email addresses

5 lines
0
Checked
0
Valid
0
Invalid

Paste one email per line and check them — each line gets its own pass or fail, with a reason if it fails.

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Email validator Password strength checker SPF record checker Dead link checker

All 5 checkers

What gets flagged

Six formatting rules

Missing @ symbol

Every address needs exactly one @ separating the local part from the domain.

Multiple @ symbols

multiple@@symbols.com is rejected — a valid address has exactly one.

Missing domain extension

An address needs a . after the domain name — user@example alone isn't enough.

Starts or ends with @

@invalid.com and invalid.email@ are both missing the part on the other side.

Invalid characters

Most punctuation outside . @ - and word characters isn't allowed. A plain space is a special case — see the FAQ.

Typo'd TLD

Common substitutions like .c0m, .n3t, .0rg and .1nfo are flagged with the domain you probably meant.

How it works

Three steps, no account

1

Paste your list

One address per line. Works for five addresses or five hundred — there's no server round-trip to wait on.

2

Check the summary

The count of valid and invalid addresses appears instantly, before you scroll to see which ones failed.

3

Fix what's flagged

Each failing line shows the specific reason, so you're not left guessing which character broke it.

FAQ

Common questions

How is this different from the Email Validator?
They run the same formatting check — this page exists as a more direct destination for "is this email malformed" searches specifically, rather than general validation. If you're already on one, there's no need to also check the other.
Does this confirm the email actually exists?
No — it checks formatting only. A correctly formatted address can still belong to no one. Confirming a mailbox is live requires contacting the recipient's mail server directly, which this tool intentionally doesn't do.
Is my list of addresses sent anywhere?
No. Checking runs entirely in your browser using a regular expression — nothing is uploaded, logged, or stored, which matters if the list you're checking is a customer or contact database.
Why did a real email address get flagged?
The rules here follow the common, practical shape of an email address rather than the full formal spec, which technically allows some unusual characters almost no real provider accepts. A space in the local part (before the @) is always rejected, for example — real mail systems don't accept it either, even though the formal spec has a quoted-string exception for it.
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Related

People who used this also used

Email validator The same check, framed around general validation.
SPF record checker Check whether a domain's outbound mail is set up correctly.
Dead link checker The same bulk-list, per-row pattern — for URLs instead of emails.
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Email Malformed Checker

Cleaning up an email list? Our Email Malformed Checker helps you identify invalid and malformed email addresses instantly. Paste a list of emails, and we'll separate the good from the bad.

How to Use

1. Paste Emails

Enter your list of email addresses in the text box. One email per line.

2. Check

Click "Check Emails". The tool analyzes each address for syntax errors.

3. Review Results

  • Valid Emails: Correctly formatted addresses.
  • Invalid Emails: Addresses with errors (missing @, invalid characters, typos).
  • Reason: We tell you why an email is invalid (e.g., "Missing domain", "Invalid TLD").

Common Errors Detected

  • Typos: Like [email protected] instead of gmail.com (checks for common TLD patterns).
  • Syntax: Missing @ symbols, spaces in addresses, double dots.
  • Structure: Missing domain extensions (like .com or .net).
  • Characters: Invalid characters that aren't allowed in email addresses.

Why Validate Emails?

  • Reduce Bounce Rates: Sending to invalid emails hurts your sender reputation.
  • Clean Data: Keep your user database accurate and useful.
  • Save Money: Don't pay for marketing emails sent to non-existent addresses.

Technical Details

This tool performs syntax validation. It checks if the email address follows standard formatting rules (RFC 5322). It does not send an email to verify if the inbox actually exists, but it catches almost all formatting errors and typos.