mailboxlayer API
Overview
mailboxlayer is an email validation API that checks whether an email address is syntactically correct, has a valid MX record, and is not a disposable address. It returns a detailed validation result including a quality score to help you filter out bad sign-ups. A useful tool for keeping your mailing lists clean and reducing bounce rates.
Beginner Tip
The free tier allows 100 requests per month and returns all validation fields, which is enough to prototype an email validation feature. Use the smtp_check field with caution — it performs a live SMTP handshake and may increase latency significantly.
Available Data
Example Response
{
"message_id": "msg_abc123def456",
"status": "delivered",
"to": "[email protected]",
"subject": "Welcome!",
"timestamp": "2025-01-15T10:30:00Z"
} Field Reference
email The email address that was validated format_valid Whether the email address has a valid syntax format mx_found Whether a valid MX record exists for the email domain smtp_check Whether the mailbox exists on the mail server (SMTP handshake result) disposable Whether the email is from a known disposable or temporary email provider score Overall quality score from 0 to 1 indicating email deliverability confidence Implementation Example
const url = "https://mailboxlayer.com/";
// Replace headers or query params with the values required by this API.
const response = await fetch(url, {
headers: {
"X-API-Key": "YOUR_API_KEY"
}
});
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data); What Can You Build?
Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.
Common Errors & Troubleshooting
Matrix Score Breakdown
Partially tested on Apr 5, 2026
Technical Specifications
Alternatives to mailboxlayer
Technical alternatives for different use cases.
Detects disposable/temporary email addresses
Blocking signups from disposable email services
Full email deliverability verification
Free email validation with syntax and MX record checks
Basic email validation without paid plan
Catch-all detection and deliverability scoring
Email sending platform with built-in validation
Combined email sending and validation in one platform
Standalone email validation without sending needs
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