Real-time email intelligence

Screen every email before it enters your funnel.

A lightweight widget for signup and contact forms. Catch malformed, disposable, and non-mail-capable domains without slowing down good users.

Test an email View integration →

0 runtime dependencies 200ms debounce 2.5s fail-open timeout

DOMAIN SIGNAL MX Mail server found

@ Plausible

EMAIL ADDRESS

hello@company.com

✓ Syntax is correctly formatted

✓ Domain exists

✓ Permanent email provider

✓ Mail server found

○ Mailbox existence not checked in this prototype

✓

Safe to continueDomain and mail server checks passed.

Live validation

See the widget in action.

Try a real address, a typo such as name@gmal.com, or a disposable provider.

01 Instant syntax feedback
02 Disposable provider detection
03 Real MX and DNS plausibility

Test the validation flow

Try a real address or jump directly to an edge case.

Built for the critical path

Fast locally. Careful remotely.

The browser handles what it can immediately. The API only performs checks that need DNS.

Syntax

Validate structure in the browser with no network request or perceived delay.

Domain

Distinguish an existing DNS name from NXDOMAIN and temporary lookup failures.

Disposable

Compare the normalized domain against an auditable provider dataset.

Mail routing

Resolve MX records, null MX declarations, and standards-aware A/AAAA fallback.

Decision

Block known bad results and fail open when verification infrastructure is unavailable.

Clear at every moment

Six states. No ambiguity.

Accessible status messages communicate progress and outcomes without relying on color alone.

IdleReady when you are

Waiting for a complete address.

CheckingLooking up the domain

Debounced and cancellable.

PlausibleDomain and routing confirmed

Mailbox existence not checked in this prototype.

InvalidNo mail route found

Submission is blocked.

DisposablePermanent email needed

Throwaway provider detected.

UnknownSafe to continue

Verification failed open.

Developer integration

One attribute.
One script. Done.

Drop the widget into an existing form. It discovers the hosted verification endpoint from its own script URL, or accepts an explicit override.

✓ Vanilla JavaScript ✓ Framework agnostic ✓ Accessible by default ✓ Race-condition safe

signup.html

<!-- Your existing form -->
<form>
  <label for="email">Work email</label>
  <input
    id="email"
    type="email"
    data-inboxvalid
  />
</form>

<script
  src="https://validate.kethanvr.tech/inboxvalid.js"
  defer
></script>

Honest by design

What this prototype verifies.

Included

✓ Browser syntax checks
✓ Disposable-domain detection
✓ MX and A/AAAA DNS checks
✓ Null MX handling
✓ Timeout and fail-open behavior

Production API territory

— SMTP mailbox probing
— Catch-all detection
— Mailbox-level deliverability
— Production risk scoring
— InboxValid private API access