Documentation / Guides

Email Validation

3 min read

Email validation catches invalid addresses before you send, protecting your sender reputation and reducing bounces.

Why validate emails

Every bounced email hurts your reputation:

  • High bounce rates trigger spam filters
  • ISPs may block your domain
  • You waste money on undeliverable messages
  • Engagement metrics become unreliable

Validation prevents this by checking addresses before sending.

Validation checks

Our validation performs multiple checks:

Check What it catches
Syntax Missing @, invalid characters
DNS Domain doesn’t exist
MX records Domain can’t receive email
Disposable Temporary/throwaway addresses
Role-based info@, support@, admin@
Catch-all Domain accepts any address
SMTP Mailbox doesn’t exist

Single email validation

Via API

curl -X POST https://api.mailingapi.com/v1/validate/single \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email": "user@example.com"}'

Response:

{
  "email": "user@example.com",
  "valid": true,
  "result": "deliverable",
  "checks": {
    "syntax": "valid",
    "dns": "valid",
    "mx": "valid",
    "disposable": false,
    "role": false,
    "catch_all": false,
    "smtp": "valid"
  },
  "suggestion": null
}

Result types

Result Meaning Action
deliverable Mailbox exists and accepts mail Safe to send
undeliverable Mailbox doesn’t exist Don’t send
risky May bounce (catch-all, etc.) Send with caution
unknown Couldn’t verify Consider manual review

Batch validation

Validate multiple emails in one request. Results are returned synchronously.

curl -X POST https://api.mailingapi.com/v1/validate/batch \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "emails": [
      "user1@example.com",
      "user2@example.com",
      "invalid@nonexistent.domain"
    ]
  }'

Response:

{
  "results": [
    {
      "email": "user1@example.com",
      "valid": true,
      "result": "deliverable",
      "checks": {
        "syntax": "valid",
        "dns": "valid",
        "mx": "valid",
        "disposable": false,
        "role": false
      }
    },
    {
      "email": "invalid@nonexistent.domain",
      "valid": false,
      "result": "undeliverable",
      "checks": {
        "syntax": "valid",
        "dns": "invalid",
        "mx": "invalid",
        "disposable": false,
        "role": false
      }
    }
  ],
  "summary": {
    "total": 3,
    "deliverable": 2,
    "undeliverable": 1,
    "risky": 0,
    "unknown": 0
  }
}

Limits:

  • Maximum 10,000 emails per request

Real-time validation

Validate during user signup:

JavaScript example

async function validateEmail(email) {
  const response = await fetch('https://api.mailingapi.com/v1/validate/single', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ email })
  });

  const result = await response.json();

  if (result.result === 'undeliverable') {
    return { valid: false, message: 'This email address appears to be invalid' };
  }

  if (result.checks.disposable) {
    return { valid: false, message: 'Disposable email addresses are not allowed' };
  }

  if (result.suggestion) {
    return { valid: true, suggestion: `Did you mean ${result.suggestion}?` };
  }

  return { valid: true };
}

Form integration

<input type="email" id="email" onblur="checkEmail(this.value)">
<span id="email-status"></span>

<script>
async function checkEmail(email) {
  const status = document.getElementById('email-status');
  const result = await validateEmail(email);

  if (result.valid) {
    status.textContent = result.suggestion || '✓ Valid';
    status.className = 'valid';
  } else {
    status.textContent = result.message;
    status.className = 'invalid';
  }
}
</script>

Typo suggestions

We detect common typos and suggest corrections:

{
  "email": "user@gmial.com",
  "valid": false,
  "result": "undeliverable",
  "suggestion": "user@gmail.com"
}

Common corrections:

  • gmial.com → gmail.com
  • gamil.com → gmail.com
  • outloo.com → outlook.com
  • yahooo.com → yahoo.com

Disposable email detection

Block temporary email addresses:

{
  "email": "temp123@10minutemail.com",
  "valid": true,
  "result": "risky",
  "checks": {
    "disposable": true
  }
}

We maintain a database of 100,000+ disposable domains including:

  • 10minutemail.com
  • guerrillamail.com
  • tempmail.org
  • throwaway.email

Role-based email detection

Identify generic addresses:

{
  "email": "info@company.com",
  "valid": true,
  "result": "risky",
  "checks": {
    "role": true
  }
}

Role-based addresses often have:

  • Multiple recipients
  • Higher complaint rates
  • Lower engagement

Common role addresses:

  • info@, support@, sales@
  • admin@, webmaster@, postmaster@
  • contact@, help@, no-reply@

Catch-all detection

Identify domains that accept all addresses:

{
  "email": "anything@catch-all-domain.com",
  "valid": true,
  "result": "risky",
  "checks": {
    "catch_all": true
  }
}

Catch-all domains accept any address, so we can’t verify if the specific mailbox exists. Higher risk of bounces.

Best practices

  1. Validate at signup — Catch bad addresses immediately
  2. Re-validate old lists — Emails go bad over time
  3. Remove undeliverable — Don’t send to known-bad addresses
  4. Consider risky emails — Decide your tolerance level
  5. Use suggestions — Help users fix typos
  6. Block disposables — If appropriate for your use case
  7. Monitor bounce rates — Validation isn’t 100% accurate

Validation strategies

Conservative (recommended for transactional)

Send only to deliverable:

if (result.result === 'deliverable') {
  sendEmail(email);
}

Moderate (balanced approach)

Send to deliverable and some risky:

if (result.result === 'deliverable' ||
    (result.result === 'risky' && !result.checks.disposable)) {
  sendEmail(email);
}

Aggressive (maximum reach)

Send unless explicitly undeliverable:

if (result.result !== 'undeliverable') {
  sendEmail(email);
}

Pricing

Validation is billed per check:

Volume Price per validation
First 1,000 Free
1,001 - 10,000 $0.005
10,001 - 100,000 $0.003
100,001+ $0.001

Bulk validation is more cost-effective than individual checks.

Next steps