Authentication

The MX18 Email Validation API uses the same authentication header name as the MX18 Mail Send APIs.
You need to acquire your unique Email Validation API Key from our support team.

Authentication method

All requests to the Email Validation API must include your MX18 API key in the request headers.

x-api-key: <YOUR_MX18_API_KEY>

API keys are scoped at the account level
Permissions and rate limits follow your existing MX18 plan
Requests without a valid API key will be rejected

Example request

curl -X POST https://validate.mx18.com/evapi/check-email \
  -H 'x-api-key: <<your_api_key>>'
  -H "Content-Type: application/json" \
  -d '{
    "email": "exampleuser@gmail.com"
  }'

Security considerations

Never expose your API key in client-side applications
Rotate API keys periodically
Revoke compromised keys immediately from the MX18 dashboard
Always use HTTPS when making API requests

Data handling and privacy

Email addresses are validated in real time
No validation emails are sent to recipients
Validation data is processed transiently and not stored for marketing use
MX18 follows applicable data protection and privacy regulations

Common authentication errors

HTTP Status	Description
`401 Unauthorized`	Missing or invalid API key
`403 Forbidden`	API key does not have access to this endpoint
`429 Too Many Requests`	Rate limit exceeded

What’s next

Validate an Email – make your first validation request
Understanding the Response – interpret scores, trust bands, and insights

Need help? Contact Support or visit https://support.mx18.com