Everything mailcheck.fr verifies
to protect your deliverability
Every email address goes through 6 independent verification layers. Not a simple DNS ping, a real SMTP connection to each mail server. Certified 98.7% accuracy.
RFC 5322 syntax check
Validates every address against the full RFC 5322 standard. Detects double at-signs, forbidden characters, malformed TLDs and non-compliant formats before any network connection attempt.
DNS resolution
Queries authoritative DNS servers to confirm that the domain actually exists. A domain without a valid DNS record cannot receive emails. This check filters out expired or fictitious domains.
MX records verification
Confirms that one or more mail servers (MX records) are configured for the domain. Without a valid MX record, no email can be routed, even if the domain exists.
Direct SMTP verification
mailcheck.fr connects directly to the recipient's mail server via the SMTP protocol and simulates sending an email without actually sending one. It is the only method able to confirm that a mailbox exists and can receive messages, with no false positives.
Catch-all (wildcard) detection
Some domains accept every incoming email, whether it is addressed to a real mailbox or not. mailcheck detects these "catch-all" servers and flags them separately. You decide whether you want to include or exclude these risky addresses from your list.
Disposable address detection
A continuously updated database of more than 3,000 temporary address domains (Mailinator, Guerrilla Mail, TempMail, YOPmail…). Blocks fake sign-ups and unqualified profiles before they pollute your CRM.
Quality score 0 – 100
Each address receives an aggregated confidence score out of 100, computed from the 6 verification layers. A score ≥ 80 = reliable address. Between 50 and 79 = risky. Below that = to remove. Prioritize your sends by score.
Smart CSV import
Drag and drop your CSV file, whatever its structure. mailcheck automatically detects the column containing the email addresses, even if the file has dozens of other columns. No prior reformatting required.
Real-time processing
Track the progress of each job live with a progress bar and results that appear as they come in. No opaque wait, you watch your list get cleaned live, email by email.
Filtered or full CSV export
Export only the valid addresses, or the full file with an added status and score column. Reimport directly into Brevo, Mailchimp or your CRM without any extra handling.
REST API <200 ms
Integrate verification directly into your sign-up forms, your CRM or your data pipeline. Median latency 187 ms (P99 <200 ms). Authentication via Bearer token. Python, Node.js and PHP SDKs available.
Statistics dashboard & history
Visualize your deliverability over time: valid/invalid/risky donut chart, job history over 90 days, credit usage, weekly and monthly trends.
Open tracking (extension)
The mailcheck Chrome extension adds open tracking to Gmail and Zoho Mail. You turn tracking on per email, and you're alerted the moment it's opened, when and how many times, with the full history in your dashboard.
MCP connector for Claude
Query your tracking data in plain language from Claude. How many times a contact opened an email, how fast, who didn't open this week: the AI queries your data and answers. OAuth connection, read-only, subscribers only.
Ready to clean your list?
2 free verifications on sign-up. No credit card. Results in under 2 seconds.