Signup validation
Give a specific correction prompt before attempting a mailbox check. Avoid silently rewriting a visitor’s address.
Instant · browser-safe
Email syntax checker
Validate the structure of an email address before doing slower DNS or mailbox checks.
Checks length, local part, @ placement, domain labels and common syntax rules.
What this check does
Syntax validation answers one narrow question: does the address look structurally valid? It does not prove the domain exists or that a mailbox can receive mail. For that, use the full email checker.
Common invalid email formats
Missing @ symbols, repeated dots, a local part longer than 64 characters, malformed domain labels, and addresses without a valid domain suffix are rejected.
Put the result to work
Separate a formatting error from a mailbox problem
A syntax check is the first pass for a copied address, a signup field or an imported contact. It checks the spelling pattern used by this tool. DNS and mailbox checks answer separate questions.
Paste the address alone
Remove display names and angle brackets. Keep punctuation that belongs to the local part.
Read the format result
A rejected pattern may be malformed or outside the practical syntax subset this checker accepts.
Check the destination next
Once the format passes, check the domain and mail routing before treating the address as usable.
Worked examples
What the evidence tells you
Illustrative scenarios, not live results for the addresses or records shown. Open a scenario to see the next action.
01alex+receipts@example.com
Supported format
The plus tag is allowed by this checker. A pass does not establish that example.com receives mail.
Next action Keep the tag, then check mail routing.
02alex..lee@example.com
Unsupported format
Consecutive dots in the local part are rejected by this checker.
Next action Ask the person to confirm the spelling.
03Alex <alex@example.com>
Display name included
A display-name wrapper is not a single address input.
Next action Paste only alex@example.com.
Use it with a purpose
Where this tool fits
Spreadsheet review
Find copied labels, malformed domains and repeated dots before checking a larger list.
Before you decide
Questions about this tool
Does a syntax pass mean the inbox exists?
No. It only means the address meets this checker’s format rules. A correctly formatted address can point to a nonexistent domain.
Are all standards-compliant addresses accepted?
No. Quoted local parts and some internationalised formats are outside this tool’s practical subset. Confirm those addresses through a suitable mail system.
Should I remove plus tags?
No. Preserve the submitted address. Tags can be used to route or organise mail.