Email Tools
Email Syntax Checker
Validate an email address’s syntax against the real rules, locally.
✓ Free
✓ No account
◉ Runs on this device
Email Tools
Powering up the tool…
TOOL EMAIL-SYNTAX
What this tool does
About the email syntax checker
Local-part and domain rules, length limits, plus-addressing explained — with the honest line that mailbox existence needs more than syntax.
How to use it
- Enter the address — it is checked locally and sent nowhere.
- Read the verdict and each rule applied.
- Note the plus-addressing and IDN observations where present.
- Remember the boundary: valid syntax, existing mailbox and deliverable address are three different facts.
Useful for
- Check why a form keeps rejecting a legitimate-looking address.
- Understand what plus-addressing in an address means.
- Validate a batch source’s formatting rules against reality.
Straight answers
Email Syntax Checker FAQ
Why do some sites reject my valid address?
Because most email regexes are wrong: plus signs, newer TLDs and internationalised domains are all legal and all commonly refused. This checker follows the actual grammar, so you can tell whose bug it is.
Can any tool verify a mailbox exists?
Only by conversing with the receiving mail server — a network probe this local tool deliberately never makes, and one many servers refuse to answer honestly anyway. Syntax is checkable truth; existence is a delivery-time fact.