Developer API

Email Validation API

One API Call. Complete Email Verification.

Simple REST API for real-time email validation. Sub-500ms response times, structured JSON responses, and comprehensive documentation. Integrate in minutes.

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Works with REST Node.js Python PHP cURL
Features

Powerful API Features

Real-time Verification

Verify emails instantly with SMTP-level accuracy. Results in milliseconds.

Batch Processing

Process multiple emails in a single request for efficient verification.

Structured JSON

Clean, consistent JSON responses. Easy to parse and integrate.

Sub-500ms Response

Lightning-fast verification suitable for signup forms and checkout.

API Key Auth

Simple API key authentication. No OAuth complexity needed.

GDPR Compliant

Fully GDPR and CCPA compliant. Your data is always protected.

Inbox Protection Data

Every response includes email_security and protection_level fields — detect enterprise gateways automatically.

Integration

Simple Integration

One API call to verify an email address.

Request

POST /v1/validate HTTP/1.1
Host: api.mailrook.com
Content-Type: application/json
Authorization: Bearer YOUR_API_KEY

{
  "email": "[email protected]"
}

Response

{
  "data": {
    "email": "[email protected]",
    "username": "test",
    "domain": "example.com",
    "mx_record": "mx.example.com",
    "provider": "custom",
    "score": 95,
    "result": "deliverable",
    "reason": null,
    "domain_status": null,
    "did_you_mean": null,
    "isv_format": true,
    "isv_domain": true,
    "isv_deliverable": true,
    "isv_nocatchall": true,
    "isv_nodisposable": true
  },
  "code": 0,
  "message": "ok"
}

Mistyped domain

When a domain cannot exist — .cov is not a top-level domain — we answer without waiting on DNS and tell you what the user most likely meant, so you can offer a correction instead of losing the signup. 

{
  "data": {
    "email": "[email protected]",
    "domain": "gmail.cov",
    "score": 0,
    "result": "undeliverable",
    "reason": "invalid_domain",
    "domain_status": "unknown_suffix",
    "did_you_mean": "[email protected]",
    "isv_format": true,
    "isv_domain": false
  },
  "code": 0,
  "message": "ok"
}

domain_status is unknown_suffix when the top-level domain does not exist, or malformed when the address is not a valid hostname at all. It stays null whenever DNS was actually consulted, including for a real domain that simply has no mail servers. did_you_mean is only ever set for an undeliverable address, and is null when no correction is confident enough to show.

Integration Methods

Multiple Integration Options

REST API

Direct HTTP calls to verify emails. Perfect for any language or framework.

View REST Docs →

Any Language

Standard JSON over HTTP. Works with Node.js, Python, PHP, cURL, and any HTTP client.

View Docs →

MCP Server

Connect your AI assistant to email validation tools.

Learn More →
Performance

Production-Ready Infrastructure

<500ms

Response Time

Average verification completes in milliseconds.

99.9%

Uptime

Enterprise-grade SLA with redundancy across regions.

25

Free Daily Checks

25 verifications per day on the free tier.

99.9%

Accuracy

Industry-leading verification accuracy with SMTP checks.

Use Cases

Common Integration Scenarios

Signup Validation

Verify email during user registration to prevent invalid signups and improve data quality immediately.

Real-time response ideal for forms

Form Validation

Check emails as users submit forms to catch typos and invalid addresses before processing.

Sub-500ms for instant feedback

CRM Hygiene

Keep your CRM contacts clean by verifying emails on sync and new additions.

Batch API for bulk operations

Pipeline Processing

Integrate into your data pipeline to maintain list quality automatically.

Batch processing at scale

Explore More Products

MailRook offers a complete suite of email validation and list cleaning solutions.

Email Verification

Verify single emails in real-time

Signup Protection

Block fake & disposable signups

List Cleaning

Clean and maintain email lists

MCP Server

Connect AI to email validation
Questions?

API Frequently Asked Questions

Use API key authentication. Include your API key in the Authorization header as a Bearer token: Authorization: Bearer YOUR_API_KEY. Generate your API key from your account dashboard.
Responses include: email address details, accuracy score (0-100), result status (deliverable/risky/undeliverable), validation flags for format, domain, deliverability, catch-all, disposable, and role-based detection, plus MX record and provider information. Mistyped domains also return a did_you_mean correction ([email protected] becomes [email protected]) and a domain_status explaining why the domain cannot exist.
Free tier: 25 verifications per day. Paid plans include higher limits depending on your subscription level. Enterprise customers can request custom rate limits. Check your account dashboard for your current rate limit.
Yes! The API supports batch verification. Send multiple emails in a single request. Each email in the batch will be verified and returned in the response. Batch requests use the same rate limits as individual requests.
Absolutely. The MailRook API is enterprise-grade with 99.9% uptime SLA, sub-500ms response times, distributed across multiple regions, and fully GDPR/CCPA compliant. Suitable for production use at any scale.
You can use the REST API directly with any language or HTTP client. The API uses standard JSON over HTTP, making integration straightforward with cURL, Node.js, Python, PHP, or any other platform. Check the API documentation for usage examples.

Get Your API Key Today

Start verifying emails in minutes. Free tier includes 25 daily verifications. No credit card required.

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