Isolate · Validation API

Email Validation API

Validate email addresses at the point of capture. Catch typos, disposable emails, and high-risk addresses before they damage your list quality and sender reputation.

Start free API documentation

cURL Node SMTP

# Send a critical email through a routing policy
curl -sS -X POST 'https://app.sendarix.com/v1/email/send' \
  -H 'Content-Type: application/json' \
  -H 'X-API-Key: YOUR_API_KEY' \
  -H 'Idempotency-Key: otp_8842' \
  -d '{"to":"user@acme.com","template":"password_reset","routing_policy":"transactional-critical"}'

const sendarix = require("sendarix")(process.env.SENDARIX_KEY);

await sendarix.email.send({
  to: "user@acme.com",
  template: "password_reset",
  routingPolicy: "transactional-critical",
  idempotencyKey: "otp_8842"
});

# Drop-in SMTP — keep your integration, gain a control plane
host:     smtp.sendarix.com
port:     587  (STARTTLS)
username: "your_sending_key"
header:   X-Sendarix-Policy: transactional-critical

Validate before you send

Every hard bounce starts with an address you should have caught.

Bad addresses cost money and reputation. Validation at the point of capture prevents undeliverable mail upstream — before it ever touches your sender reputation.

Common sources of bad addresses: typos (user@examplecon.com), disposable domains (mailinator.com), role accounts (info@, admin@), and high-risk domains that consistently bounce or complain.

Validation checks performed

Each address runs through multiple checks. Syntax is fast but shallow; MX lookup catches the majority of undeliverable addresses.

Syntax validation

RFC 5321/5322 compliant format check. Rejects malformed addresses: missing @, invalid characters, malformed domain labels.

MX record lookup

Verifies the domain accepts mail by checking MX DNS records — the most important check, catching domain typos that syntax misses.

Disposable email detection

Checks a real-time database of known disposable providers. These bounce immediately, flag spam traps, and offer no business value.

Role account detection

Identifies role-based addresses (info@, admin@, support@) that belong to groups rather than individuals and engage poorly.

Deliverability score

Each address gets a 0–100 score from historical data, domain reputation, and risk factors. Enforce a minimum threshold at signup.

Suggestion engine

On a detected typo, the API returns a correction: user@gmial.com → user@gmail.com — catching the most common domain typos automatically.

API request and response

Validate a single address

GET /v1/validate?address=user@example.com
Authorization: Bearer sk_live_...

Deliverable response

{
  "address": "user@example.com",
  "result": "deliverable",
  "score": 92,
  "checks": {
    "syntax": "pass",
    "mx": "pass",
    "disposable": "pass",
    "role_account": "pass"
  },
  "suggestion": null,
  "risk_factors": []
}

High-risk response

{
  "address": "user@mailinator.com",
  "result": "undeliverable",
  "score": 0,
  "checks": {
    "syntax": "pass",
    "mx": "pass",
    "disposable": "fail",
    "role_account": "pass"
  },
  "suggestion": null,
  "risk_factors": ["disposable_email_domain"]
}

Where to validate in your application

Signup & registration forms

Validate on blur or submit, showing inline correction on typos. This alone can cut bounce rates 15–30% on new-user acquisition flows.

Checkout & account creation

Validate before completing a transaction. An undeliverable confirmation means the customer has no record of their purchase if something goes wrong.

Import & bulk upload

Validate all addresses before adding them to a list. Results return asynchronously via webhook for large imports — add only confirmed-deliverable addresses.

Onboarding email capture

If you capture email during an onboarding wizard, validate there — catch the problem while the user is engaged enough to fix a typo.

Validation thresholds

Not every failure should block a user. Set thresholds to match your risk tolerance.

Allow

Score 80+. All critical checks pass. Safe to send.

Review

Score 50–79. Suggest a correction to the user and flag for re-validation.

Block

Score below 50. Disposable domain, typo without a clear suggestion, or MX failure.

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Integrate email validation in minutes

REST API with SDKs for Python, Node.js, Ruby, and Go. Validation results return in under 100ms for real-time form integration.

API documentation SMTP relay setup