Lab tool / domain probe
Free Email Validator
Check syntax, domain health, MX records, and common email risks. Complete addresses stay in your browser; only unique domain names leave it for DNS checks.
- Syntax
- Domain
- MX
- Disposable
- Role
- Typos
Email signal analysis
Inspect an address or a whole list.
Ready for a specimen.
Six signals, one honest result
What the validator checks
Each address is classified as Valid Domain, Risky, Invalid, or Unknown. The confidence score is deterministic and capped at 90 because mailbox-level SMTP verification is not included.
Syntax
Practical address parsing, local-part limits, dot placement, domain labels, IDNs, and normalization.
Domain + MX
Cloudflare DNS-over-HTTPS checks for MX records, Null MX, NXDOMAIN, and RFC-compatible A/AAAA fallback.
Risk signals
Lazy-loaded disposable-domain data, role prefixes, duplicates, public providers, and curated typo suggestions.
Browser-first by design
Your list is not our dataset.
CSV and TXT files are read locally. Complete addresses, local parts, duplicates, and results are never sent to the validator API or stored in D1. Before a request is made, the browser extracts and deduplicates domains, then sends batches of at most 15.
The server stores reusable domain intelligence only: DNS status, MX records, provider inference, cache version, and expiration. If DNS is temporarily unavailable, the result is Unknown—not Invalid.
Validation pipeline
How it works
- 01Parse locally
Syntax, normalization, duplicate, role, disposable, provider, and typo signals stay in the browser.
- 02Probe unique domains
Cached intelligence is reused; only misses perform controlled MX and fallback DNS queries.
- 03Combine the evidence
Versioned rules produce a status, capped domain-confidence score, reasons, and a client-side CSV export.
Clear limits
What this can—and cannot—verify
It can confirm whether the address is well-formed and whether its domain publishes a usable mail route. It can also surface common risks.
It cannot confirm that a named mailbox exists, accepts messages, is a catch-all, or will never bounce. Those claims require separate SMTP infrastructure and are intentionally absent from V1.
Field notes
Email validation FAQ
Does this tool confirm that a mailbox exists?
No. Version 1 checks syntax, domain DNS, mail routes, and risk signals. It does not perform an SMTP mailbox check, so it never claims that a specific inbox exists.
Does my email list get uploaded?
No. Parsing, duplicate detection, risk checks, CSV handling, and exports happen in your browser. Only deduplicated domain names are sent to the same-origin API for DNS and MX checks.
Why can a valid domain still be marked risky?
A domain can accept mail while the address is disposable, role-based, duplicated, mistyped, or dependent on an unusual implicit mail route. Those signals are useful warnings, not proof that the address is unusable.
What does Unknown mean?
Unknown means the DNS resolver or validation infrastructure could not give a reliable answer right now. The tool keeps uncertainty separate from Invalid so temporary failures do not become false negatives.