Email Verification API & Bulk Email Validation

Why EmailZeno

Engineered to protect your sender reputation.

Built by engineers who got blacklisted the hard way. Every feature exists to keep your IPs clean — not just tick a marketing box.

Mailbox checks without delivery

We probe each receiving server with a handshake-only sequence and disconnect before any message data is transmitted. The recipient sees a clean check, nothing more.

Per-domain rate limiting

Concurrency capped at 5 simultaneous connections per recipient domain (3 for Gmail / Yahoo / Outlook). Your IP stays clean.

30-min soft-block cooldown

When error rate on a domain spikes past 30% in 60 seconds, we back off automatically for 30 minutes. No manual intervention needed.

Confidence scoring

Results arrive as deliverable / risky / undeliverable with a numeric confidence score — not just a binary pass/fail.

MX record caching

Redis-backed MX resolution cuts latency and DNS load. Cache TTL respects the record's own TTL — always fresh, never stale.

Native ESP integrations

Push cleaned lists directly to Mailchimp, Brevo, MailerLite, GetResponse, ConvertKit, ActiveCampaign, Mailwizz, and Campaign Monitor.

REST API + signed webhooks

Single-address sync or async bulk batches. Results posted to your endpoint via HMAC-SHA-256 signed webhooks — verify every payload.

EU-hosted, GDPR-aligned

Servers in Nuremberg. All list data encrypted at rest; auto-purged 30 days after verification completes. DPA on request.

Credit refund on bounce

If a result we marked deliverable bounces hard within 7 days, the credit returns to your balance — automatically, no ticket needed.

How it works

Four stages. Zero guesswork.

Every address runs through the same deterministic pipeline. No black boxes, no machine-learning hand-waving — just protocols doing what protocols do.

Syntax & list check

Regex validates format. Disposable-domain and role-address lists filter obvious junk.

Instant — no network call needed.

MX lookup

DNS queries resolve the recipient domain's mail-exchange records.

Redis-cached per record TTL — repeat checks are free.

Mailbox probe

EHLO → MAIL FROM → RCPT TO → QUIT. The receiving MTA confirms mailbox existence.

No DATA command. No message ever sent. Rate-limited per domain.

Result + confidence

Returns valid / risky / invalid / unknown with a numeric confidence score.

Credits refunded automatically on hard bounce within 7 days.

Get 1,000 free verifications

Developer-first API

Stop bad emails at signup.
One API call.

One endpoint, one JSON response. HMAC-signed webhooks for bulk jobs. SDKs optional — any HTTP client works in five lines or less.

<200 ms median latency
Sync or async (webhook)
5 SDKs + raw cURL

Read the docs

cURL

# Single address verification
curl -X POST https://app.emailzeno.com/api/v1/verify \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email": "[email protected]"}'

JavaScript

const res = await fetch('https://app.emailzeno.com/api/v1/verify', {
  method: 'POST',
  headers: {
    'Authorization': `Bearer ${YOUR_API_KEY}`,
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({ email: '[email protected]' }),
});
const { data } = await res.json();
console.log(data.status, data.confidence_score);

PHP

// Requires: composer require guzzlehttp/guzzle
use GuzzleHttp\Client;

$client = new Client(['base_uri' => 'https://app.emailzeno.com']);
$resp   = $client->post('/api/v1/verify', [
    'headers' => ['Authorization' => 'Bearer ' . $apiKey],
    'json'    => ['email' => '[email protected]'],
]);
$data = json_decode($resp->getBody(), true)['data'];
echo $data['status'] . ' (' . $data['confidence_score'] . '%)';

Python

# pip install requests
import requests

resp = requests.post(
    "https://app.emailzeno.com/api/v1/verify",
    headers={"Authorization": f"Bearer {api_key}"},
    json={"email": "[email protected]"},
    timeout=10,
)
data = resp.json()["data"]
print(data["status"], data["confidence_score"])

Response shape: {"data":{"status":"valid","confidence_score":98,"mx_found":true,...}}. Full reference at emailzeno.com/api.

How we compare

Same accuracy. A fraction of the price.

Honest, side-by-side breakdown against the four most-trusted providers. Pricing reflects their public pay-as-you-go rates at time of writing.

	EmailZeno Best value	ZeroBounce	NeverBounce	Emailable	Kickbox
Pricing
10,000 credits	$49	$65	$60	$50	$80
100,000 credits	$179	$325	$400	$350	$700
1,000,000 credits	$999	$2,400	$3,000	$2,100	$4,000
Flat-rate unlimited plan	✅ $42/mo	❌	❌	❌	❌
Accuracy & features
Accuracy	99.6%	99%+	99%+	99%+	99%+
Bulk list upload
Real-time API
Email bounce validator
Spam-trap detection
Abuse email detection
Disposable / role detection
Integrations (Zapier, etc.)
24/7 support

Competitor prices sourced from public pricing pages, reviewed July 2026. Subject to change at the provider's discretion.

Start free See full pricing

Pricing

Pricing that scales with your list — not your headcount.

Pay only for what you verify. No per-seat fees, no annual lock-in, credits never expire.

Free

1,000 verifications included

Kick the tyres. No card needed.

Real-time mailbox probing
Confidence scoring
REST API access
5 free tries (no account)

Start free

Prefer to pay once? Buy credits that never expire.

No subscription. Use credits whenever you need them.

10,000 Credits

^$49.00 one-time

10,000 credits · never expire

Buy 10,000 credits

50,000 Credits

^$119.00 one-time

50,000 credits · never expire

Buy 50,000 credits

Best value

100,000 Credits

^$179.00 one-time

100,000 credits · never expire

Buy 100,000 credits

See all top-up packs with Polar, Payssion, and crypto payment options.

Credits never expire

Unknown results free

No lock-in contracts

Email support on all plans

Need higher volume? Talk to us — or see the full pricing page for the feature comparison table.

FAQ

Straight answers to the questions we get most.

The Unlimited plan gives you an unlimited monthly quota at a flat $39/month — no credit counters, no overage fees. A 50,000/day fair-use cap applies to prevent a single tenant from monopolising shared verification capacity. In practice, 50k/day equals 1.5 M verifications/month, which covers the vast majority of use cases. If you routinely need more than 50k/day, contact us about Scale or a custom plan.

Above 99% on most domains. Catch-all servers and greylisted hosts cannot be probed definitively without sending actual mail — which we never do. Those return as "risky" with a confidence score so you can decide whether to include them.

No. We never issue the DATA command, so no message is delivered and no content crosses the wire. Per-recipient-domain concurrency limits (5 connections max, 3 for major providers) and 30-minute soft-block cooldowns prevent the sustained probing patterns that lead to blacklisting.

Yes. Servers are in Nuremberg, Germany. All list data is encrypted at rest and automatically purged 30 days after verification completes. A Data Processing Agreement (DPA) is available on request — email [email protected].

1,000 verifications are included when you sign up — no credit card required. After that, paid monthly subscriptions (Solo / Growth / Scale) include a generous monthly allowance. You can also buy credit packs if your volume is irregular.

Yes. Every account, including free, gets REST API access. The free tier is rate-limited to 60 requests/minute on the single-verify endpoint. Bulk async jobs require a paid plan.

If an address we marked deliverable produces a hard bounce within 7 days of verification, the credit is automatically refunded to your balance. No support ticket needed.

Single-verify: 60 requests/minute on Free, 300/minute on Solo, 600/minute on Growth, 1 200/minute on Scale. Bulk batch endpoint: limited by your credit balance and account tier. See the API docs for full details.

Not in a single call — our async bulk endpoint accepts up to 50 000 addresses per job. Large lists should be split into multiple jobs. Results are delivered via HMAC-signed webhook when the job completes.

Log in to your dashboard, go to Billing, and downgrade or cancel anytime. Monthly plans are billed at the start of each period; cancellation stops the next charge. Credits already purchased never expire.

Yes — email [email protected] with your monthly verification estimate. We handle 10 M+ address lists routinely and can discuss per-credit pricing for high-volume accounts.

Don't burn
your sender reputation.

Check one address before you trust the list.

Engineered to protect your sender reputation.

Mailbox checks without delivery

Per-domain rate limiting

30-min soft-block cooldown

Confidence scoring

MX record caching

Native ESP integrations

REST API + signed webhooks

EU-hosted, GDPR-aligned

Credit refund on bounce

Go deeper — pick your path.

Bulk list cleaning

Signup form validation

vs ZeroBounce

vs NeverBounce

Email Checker

Blacklist Checker

Four stages. Zero guesswork.

Syntax & list check

MX lookup

Mailbox probe

Result + confidence

Stop bad emails at signup.
One API call.

Same accuracy. A fraction of the price.

Pricing that scales with your list — not your headcount.

Prefer to pay once? Buy credits that never expire.

Plugs into the tools you already use.

Straight answers to the questions we get most.

Talk to a human.

Clean lists ship faster.
Start free.

Don't burn your sender reputation.

Check one address before you trust the list.

Engineered to protect your sender reputation.

Mailbox checks without delivery

Per-domain rate limiting

30-min soft-block cooldown

Confidence scoring

MX record caching

Native ESP integrations

REST API + signed webhooks

EU-hosted, GDPR-aligned

Credit refund on bounce

Go deeper — pick your path.

Bulk list cleaning

Signup form validation

vs ZeroBounce

vs NeverBounce

Email Checker

Blacklist Checker

Four stages. Zero guesswork.

Syntax & list check

MX lookup

Mailbox probe

Result + confidence

Stop bad emails at signup.One API call.

Teams shipping email at scale.

Same accuracy. A fraction of the price.

Pricing that scales with your list — not your headcount.

Prefer to pay once? Buy credits that never expire.

Plugs into the tools you already use.

Straight answers to the questions we get most.

What does Unlimited actually mean?

How accurate are your verification results?

Will probing emails harm my IP reputation?

Is EmailZeno GDPR-compliant?

How does the free plan work?

Does the free plan include API access?

What happens if a "deliverable" result bounces?

What is your API rate limit?

Can I verify an entire list in one API call?

How do I cancel or change my plan?

Do you offer custom volume pricing?

Talk to a human.

Clean lists ship faster.Start free.

Don't burn
your sender reputation.

Stop bad emails at signup.
One API call.

Clean lists ship faster.
Start free.