---
title: "Free email address checker: syntax, domain, MX"
url: "https://lookvalid.com/tools/email-address-checker.md"
canonical_url: "https://lookvalid.com/tools/email-address-checker"
last_updated: "2026-10-29"
type: "tool"
summary: "Check one email address for free. See whether the syntax is valid, the domain exists and has mail servers, and whether it is a disposable."
related: ["https://lookvalid.com/docs/api/email-domain-check.md"]
---

# Free email address checker: syntax, domain, MX

> **For AI agents:** the complete index of LookValid pages is [llms.txt](https://lookvalid.com/llms.txt). Every page is also served as markdown at its URL plus .md.

Check one email address for free. See whether the syntax is valid, the domain exists and has mail servers, and whether it is a disposable.

Paste one email address to find out whether it is likely to receive mail, and why. We check the spelling rules, the domain, its mail servers and the throwaway-address lists. We do not contact the mailbox.

## Facts

- Free, no account needed. Rate limited per visitor.
- Runs the `email-domain-check` product. The same lookup through the API costs 1 credit.
- API reference: [email-domain-check](https://lookvalid.com/docs/api/email-domain-check.md)

Syntax comes first: one @ sign, a part before it of at most 64 characters, no spaces, no doubled or edge dots, and a domain that is a valid name. Quoted forms and bracketed IP addresses are rare and count as invalid here.

Next the domain is looked up in public DNS. A name that does not exist stops the check, since mail to it can never arrive. A domain that exists is asked for its MX records, the list of servers that take its mail.

The domain is then compared with open lists of disposable mail services and free mailbox providers, and the part before the @ is compared with common shared names such as info, sales and support. All of this uses DNS and lists. The mail server is never contacted.

## Related

- [Email Domain Check reference](https://lookvalid.com/docs/api/email-domain-check.md)