Email Validation API: Best Practices for Developers

Email validation is crucial for any application that collects user data. This guide covers the different approaches to email validation and how to implement it using a simple API.

Why Validate Emails?

Email validation helps you:

• Reduce bounce rates: Invalid emails hurt your sender reputation
• Improve deliverability: Clean lists get better inbox placement
• Save costs: Don't pay to send to invalid addresses
• Better UX: Catch typos before users submit
• Prevent abuse: Block obviously fake emails

Levels of Email Validation

Level 1: Syntax Validation

Check if the email follows the basic format: local@domain.tld

This catches obvious errors like missing @ symbols or invalid characters.

Level 2: Domain Validation

Verify that the domain exists and has valid MX records. This ensures the email can actually receive mail.

Level 3: Mailbox Validation

Check if the specific mailbox exists (SMTP verification). More accurate but slower and can trigger spam filters.

Using the Email Validation API

GET https://api.tinyfn.io/v1/validate/email?email=test@example.com
Headers: X-API-Key: your-api-key

{
  "email": "test@example.com",
  "is_valid": true,
  "parts": {
    "local": "test",
    "domain": "example.com"
  }
}

Implementation Examples

React Form Validation

async function validateEmail(email) {
  const response = await fetch(
    `/api/validate-email?email=${encodeURIComponent(email)}`
  );
  const data = await response.json();
  return data.is_valid;
}

// In your form handler
const handleSubmit = async (e) => {
  e.preventDefault();
  const isValid = await validateEmail(email);
  if (!isValid) {
    setError('Please enter a valid email address');
    return;
  }
  // Continue with form submission
};

Python Backend

import requests

def validate_email(email: str) -> bool:
    response = requests.get(
        'https://api.tinyfn.io/v1/validate/email',
        params={'email': email},
        headers={'X-API-Key': API_KEY}
    )
    return response.json()['is_valid']

# Usage
if not validate_email(user_email):
    raise ValueError('Invalid email address')

Best Practices

1. Validate on both client and server: Client-side for UX, server-side for security
2. Don't be too strict: Valid email formats can be surprising (e.g., user+tag@domain.com)
3. Send confirmation emails: The only 100% validation is successful delivery
4. Handle edge cases: International domains, new TLDs, etc.
5. Cache results: Don't re-validate the same email repeatedly