Email Validation API
Verify email addresses in real time. DNS lookups, MX record checks, SMTP probing, disposable detection — all in a single API call. Built for production workloads.
What the API Checks
Syntax Validation
RFC 5322-compliant format check. Catches malformed addresses, missing @ symbols, invalid characters, and incorrect domain formatting before anything else runs.
DNS & MX Records
Resolves the domain's MX records to confirm it can receive mail. Domains with no MX records are flagged as undeliverable — this catches a large class of invalid addresses fast.
SMTP Verification
Probes the mail server to check if the mailbox exists. Best-effort — some servers accept all addresses or silently reject — so results are combined with other signals for a confidence score.
Catch-All Detection
Identifies domains that accept mail to any address (catch-all). These domains always return "valid" at the SMTP level, so we flag them separately so you can decide how to handle them.
Disposable Email Blocking
Detects temporary email providers like Mailinator, Guerrilla Mail, and 10MinuteMail. Keeps your user base clean and prevents throwaway signups.
Typo Suggestions
Catches common domain misspellings (gmial.com → gmail.com) and suggests corrections. Helps users fix mistakes during signup instead of creating undeliverable accounts.
Get Started in Seconds
curl -X POST "https://api.novacheck.io/v1/email" \
-H "Content-Type: application/json" \
-H "Authorization: Bearer nc_live_YOUR_KEY" \
-d '{"emails": ["[email protected]"]}'{
"results": [{
"email": "[email protected]",
"valid": false,
"reason": "undeliverable",
"sub_reason": "no_mx",
"syntax_valid": true,
"score": 35
}],
"summary": {
"total": 1, "deliverable": 0,
"undeliverable": 1, "risky": 0, "unknown": 0
}
}That's it. One endpoint, one request, all the signals you need.Full API reference →
Common Use Cases
Signup Forms
Validate emails at registration. Catch typos and disposable addresses before the user account is created. Reduce support tickets from undeliverable confirmation emails.
Email List Cleaning
Remove invalid, disposable, and catch-all addresses from your mailing list before your next campaign. Protect your sender reputation and improve deliverability.
Fraud Prevention
Block disposable and temporary email domains at account creation. Detect catch-all domains used to create throwaway accounts. One more signal in your fraud scoring.
CRM Data Quality
Periodically validate stored email addresses to catch addresses that became invalid over time. Keep your CRM data clean without manual reviews.
Why NovaCheck
Sub-second responses
DNS and MX checks resolve in milliseconds. SMTP probes time out fast rather than hanging. Your signup flow doesn't stall.
No email stored, ever
Validated addresses are encrypted, cached temporarily (up to 24 hours) and then purged. We don't keep a database of your users' emails.
Honest signals, not false certainty
We return a score and a reason code (deliverable, undeliverable, risky, unknown) — not a binary yes/no that oversells what DNS can tell you. Catch-all and unverifiable results are flagged so you can make the call.
Test keys for development
Dedicated test environment with deterministic mock responses. Integrate and write CI/CD tests without burning through quota or making real DNS lookups.
Frequently Asked Questions
How is email validation different from email verification?
Validation checks whether an address is syntactically correct and the domain can receive mail (DNS, MX). Verification goes further by probing the mail server to confirm the mailbox exists (SMTP). NovaCheck does both — the API returns signals from each layer so you can decide what level of confidence you need.
How accurate is the validation?
DNS-based checks (syntax, domain existence, MX records) are deterministic and highly reliable. SMTP checks are best-effort — some mail servers accept all addresses (catch-all) or silently reject probes. We return a confidence score and reason code so you can interpret the result in context rather than relying on a binary valid/invalid.
Can I validate emails in bulk?
Yes. The /v1/email endpoint accepts up to 100 addresses per request. For larger lists, send multiple requests in sequence or check our bulk email validation guide for patterns.
Does the API store submitted email addresses?
Validation results are encrypted and cached temporarily (up to 24 hours) to speed up repeated lookups for the same address. After the cache entry expires, the address is gone from our systems. We don't build a database from your requests.
What happens when I hit my rate limit?
The API returns a 429 Too Many Requests response with headers showing your limit, remaining requests, and reset time. No surprise charges — over-quota requests are simply rejected until the window resets.
Start validating emails in minutes
500 free validations per month. No credit card required.