98.7% certified accuracy · GDPR compliant

Stop the B2B email bounces
that cost you 0€/month.

mailcheck.fr verifies every address on your list through a real SMTP connection, not just a DNS ping. Results in under 2 seconds, 98.7% certified accuracy, 100% French infrastructure and GDPR compliant. Ideal for B2B marketing teams that want to protect their sender reputation.

2 free verifications · no credit card · Results in <2s

Free trial No account, no credit card

Check whether an email address actually receives emails

2 free verifications per day · Create an account to do more

2,847,193
Emails verified
98.7%
Accuracy rate
<2s
Average time per verification
⚠️ A bounce rate >2% gets your domain blacklisted
📉 -40% deliverability without regular cleaning
🚨 15-25% of email lists decay every year
💸 You pay your ESP for emails that are never received

How much are your bounces really costing you?

A mere 5% bounce rate on a list of 50,000 contacts means 2,500 emails lost per campaign. With every send, you burn budget, reputation and sales opportunities. Quantify the impact in 30 seconds.

🚫
Your sender reputation is calculated by Gmail, Outlook and Yahoo over your last 30 days. A single bounce spike can trigger a global block.
💰
You pay your Brevo/Mailchimp for every email sent, valid or not. Removing the invalid ones cuts your ESP bill immediately.
📊
Every point of deliverability recovered directly increases your open rates, click rates and ultimately your email revenue.

Estimate your monthly loss

Size of your email list 50 000
1 000 500 000 1 000 000
Current estimated bounce rate 8%
0% 15% 30%
Average value of an email lead (€) 25 €
1 € 250 € 500 €
💸 What you are losing -
📦 Estimated mailcheck.fr cost -
📈 Your ROI with mailcheck -
Verify my emails for free

Results based on France 2024 industry averages · For guidance only

Your clean list in 3 steps

No-code interface or full API · import your file, get results in real time.

Step 01
📂
Import your list

Drag and drop your CSV file, paste your addresses directly or send them via the API. No configuration, immediate results.

CSV / Excel Copy-paste REST API
Step 02
Real-time verification

Our engine checks every address: syntax, DNS, MX records, SMTP, catch-all and disposable domains. Result in under 2 seconds per email.

SMTP check Disposable Catch-all MX records
Step 03
Clean list exported

Download your filtered list with a quality score per address. Re-import the clean CSV into your ESP for maximum deliverability.

Quality score CSV export Job history
Available on the Chrome Web Store

Know who opens your emails

Our Chrome extension adds open tracking right inside your inbox. You can see whether your sent emails have been read, when and how many times, with a full history in your dashboard.

Gmail Zoho Mail
Open tracking Per-email toggle Dashboard history Free up to 10 / month
New · MCP connector for Claude

Query your email data with AI

Connect your tracking data to Claude and ask in plain language: how many times a contact opened an email, how fast, who didn't reply this week. The AI queries your data and answers, with no dashboard to dig through.

Plain language Secure OAuth Read-only Included from €9/mo
Discover the MCP connector

Integrate in under 10 minutes

Our JSON API is designed for developers who want to verify emails in real time at signup. Full documentation, PHP, Python, Node.js SDKs and an API key available immediately.

Single or batch verification up to 50,000 per request
Real-time webhook for batch results
Latency <200ms in single-check (P99)
99.9% uptime SLA · Cloudflare + OVH Paris infrastructure
Verification run in France, GDPR compliant
Configurable rate limiting per endpoint
See the documentation
API · Simple verification example
cURL
Python
Node.js
# Verify an email address
curl -X POST https://api.mailcheck.fr/v1/verify
  -H "Authorization: Bearer YOUR_API_KEY"
  -H "Content-Type: application/json"
  -d '{"email":"[email protected]","options":{"catch_all":true}}'
Response 200 OK · 187ms
{
  "email": "[email protected]",
  "status": "valid",
  "score": 97,
  "checks": {
    "syntax": true,
    "dns": true,
    "mx": true,
    "smtp": true,
    "disposable": false,
    "catch_all": false
  },
  "confidence": "high"
}
98.7%
Verification accuracy
Certified on 50M+ emails tested
2M+
Emails verified per month
Growing 40% per quarter
<2s
Per verification
Median latency: 187ms
99.9%
Guaranteed uptime
Contractual SLA · Cloudflare + OVH Paris infra

Boost your deliverability today

No commitment. Change plan at any time. Cancel in one click.

Billing: Monthly
Annual 2 months free
Starter
29 /month
5,000 email verifications
  • Real-time verification
  • CSV import
  • Disposable address detection
  • Quality score per email
  • Results export
  • REST API access + API key
  • Email support within 48h
Choose Starter
Pro
299 /month
200,000 email verifications
  • Everything in Growth
  • Multi-account / sub-accounts
  • Contractual 99.9% SLA
  • White-label PDF report
  • SLA support within 8h
  • Beta access to new features
Choose Pro
Agency
499 /month
1,000,000 email verifications
  • Everything in Pro
  • 1 million verifications/month
  • SLA support within 4h + phone
  • Dedicated account manager
  • Personalized onboarding
  • Custom quote billing available

Need to verify more than 1 million emails per month?

Custom volume, dedicated SLA, guided integration. We reply in under 4h.

Contact us

All prices excl. tax · 20% VAT applicable · No monthly commitment · Annual subscription = 10 months (2 months free) · GDPR compliant · Verification run in France

They recovered their deliverability

+34% opens

We had a 12% bounce rate on our list of 80,000 contacts. Gmail was sending us to spam. After the mailcheck cleaning, we dropped to 1.2% and our open rates jumped 34% in two weeks. The ROI is obvious.

MR
Marc R.
Marketing Director · Digital agency, Reims
−62% ESP cost

I had inherited a list of 200K leads through an acquisition. 28% were invalid. mailcheck identified them in 8 minutes. I saved directly on my Brevo bill and avoided a blacklist that would have killed my launch campaign.

SL
Sophie L.
Growth Manager · SaaS startup, Paris (Series A)
8× ROI in month 1

I run a solo e-commerce shop and had never cleaned my list in 3 years. The interface is really simple, no technical skills required. In 15 minutes, my list was clean and my newsletters finally land in the primary inbox.

TP
Thomas P.
Freelancer · Lifestyle e-commerce, Lyon

Frequently asked questions

Does mailcheck.fr send an email to the recipient to verify the address?
No. mailcheck.fr connects to the recipient's mail server via the SMTP protocol and simulates the start of a send, then interrupts the connection before any email is actually transmitted. The recipient receives nothing and never knows a verification took place.
What is the difference between DNS/MX verification and SMTP verification?
DNS/MX verification confirms that the domain exists and has a mail server configured. SMTP verification goes further: it actually knocks on the server's door to confirm that the specific mailbox exists. A DNS-only tool misses roughly 15 to 20% of the invalid addresses that an SMTP tool would catch.
How does catch-all email detection work?
A catch-all domain accepts every email, regardless of the local address. mailcheck.fr detects it by testing a random, non-existent address on the domain. If the server accepts it, the domain is flagged as catch-all. Between 15 and 25% of French B2B domains are configured this way.
Is mailcheck.fr GDPR compliant? Where is my data stored?
Yes. mailcheck.fr is developed by HYPER10N TECHNOLOGIES SAS, a French company. The infrastructure runs on Cloudflare (CDN) and OVH (backend servers, Roubaix datacenter, France). Data never leaves the European Union. Find our detailed GDPR policy on the dedicated page.
Can I use mailcheck.fr with Brevo, Mailchimp or HubSpot?
Yes. mailcheck.fr integrates via the REST API or through CSV import with every emailing tool. Code examples for Brevo, Mailchimp, HubSpot, Webflow and n8n are available on the integrations page. API integration takes under 10 minutes.
How long does it take to verify a list of 50,000 emails?
Around 15 to 30 minutes depending on the distribution of domains. Addresses on well-configured domains (Gmail, Outlook) are processed in under 2 seconds each. Domains with slow servers or strict anti-spam (Office 365, Mailinblack) slightly increase the time.
What bounce rate triggers a blacklisting by Gmail?
Since February 2024, Gmail enforces a 2% spam rate threshold per campaign. Beyond that, sender reputation degrades automatically and subsequent emails land in spam. For hard bounces (non-existent addresses), a rate above 5% across several campaigns can trigger a temporary block.
What is the difference between a hard bounce and a temporary bounce?
A hard bounce (SMTP code 550) means the address does not exist or the domain is non-existent. It must be permanently removed from your list. A temporary bounce (code 452) is transient: full mailbox or unavailable server. If an address generates repeated temporary bounces over 3 to 5 attempts, treat it as a hard bounce.
Ready to stop the bounces?

Clean your list now
2 free verifications

No credit card. Setup in 3 minutes. Immediate results.

2 free verifications
No commitment
Verification run in France
GDPR compliant
Support in French