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Email Validator

Full email validation with syntax, MX, SMTP, and deliverability checks

GET 3 credits /v1/email/validate

curl "https://email.toolkitapi.io/v1/email/[email protected]" \
  -H "x-api-key: YOUR_API_KEY"

import httpx

resp = httpx.get(
    "https://email.toolkitapi.io/v1/email/[email protected]",
)
print(resp.json())

const resp = await fetch("https://email.toolkitapi.io/v1/email/[email protected]", {
});
const data = await resp.json();
console.log(data);

# See curl example

Response 200 OK

{
  "email": "[email protected]",
  "local_part": "user",
  "domain": "toolkitapi.io",
  "syntax_valid": true,
  "mx_found": true,
  "mx_records": ["mx1.toolkitapi.io", "mx2.toolkitapi.io"],
  "smtp_code": 250,
  "smtp_message": "2.1.5 OK",
  "is_deliverable": true,
  "is_disposable": false,
  "is_free": false,
  "is_role_account": false,
  "is_catch_all": null,
  "deliverability": "deliverable",
  "confidence": 0.95
}

Description

Full email validation with syntax, MX, SMTP, and deliverability checks

How to Use

1

1. Pass the email address as the `email` query parameter.

2

2. Check `deliverability` for the overall verdict — "deliverable" means safe to send.

3

3. Review `is_disposable`, `is_free`, and `is_role_account` flags for lead quality assessment.

4

4. Use `confidence` (0.0–1.0) to set your own threshold for accepting or rejecting addresses.

About This Tool

The Email Validator runs a comprehensive multi-step validation pipeline on any email address. It checks syntax against RFC 5322 rules, resolves MX records for the domain, performs an SMTP mailbox probe (RCPT TO) to verify the address exists, and detects disposable email providers, free email services, and role-based addresses.

The result includes a deliverability verdict (deliverable, risky, undeliverable, or unknown) with a confidence score, giving you a reliable signal for whether the address is safe to send to.

Use this to clean your email lists, validate sign-up forms in real-time, or assess lead quality.

Why Use This Tool

Sign-up form validation — Reject invalid or disposable emails at registration time
Email list cleaning — Validate existing contacts to reduce bounce rates before campaigns
Lead scoring — Flag role accounts and free email addresses as lower-quality leads
Deliverability optimization — Remove undeliverable addresses to protect sender reputation

Frequently Asked Questions

How does SMTP verification work?

The API connects to the domain's MX server and performs a RCPT TO probe — it asks the server if the mailbox exists without actually sending an email. A 250 response means the mailbox exists; 550 means it doesn't.

What's the difference between "risky" and "unknown"?

"Risky" means the address has characteristics that make delivery uncertain (disposable domain, role account, or inconclusive SMTP probe). "Unknown" means the validation couldn't determine deliverability at all.

Does this check actually send an email?

No, the SMTP probe only goes through the RCPT TO step of the SMTP handshake. No email is composed or delivered during validation.

Start using Email Validator now

Get your free API key and make your first request in under a minute.

Get Free API Key View Docs