Guides & documentation
Simple explanations for everyone + technical documentation for developers.
Guides
What Is Email Validation and Why It Matters
Email validation is the difference between reaching a real person and burning your sender reputation on dead addresses. Here is what it actually checks.
Good, Bad, Unknown: Reading Your Validation Results
Every CleanContact check returns one of three verdicts. Knowing what each means — and what to do with it — keeps your list clean without throwing away good contacts.
How SMTP Mailbox Verification Works
Under the hood, verifying a mailbox means starting a real SMTP conversation and stopping just before you send. Here is the dialogue, step by step.
Catch-All Domains and Why They Are Hard
Some providers accept emails sent to any address, whether it's real or not. Because of this, standard checks can sometimes be inaccurate. Here's how CleanContact determines whether an email address is valid.
Disposable Email Detection: Always-Fresh DEA Blacklists
New throwaway email domains appear every day. CleanContact keeps its disposable-address blacklist current by downloading it automatically from multiple sources.
Cut Bounce Rates and Protect Your Sender Reputation
Deliverability is a reputation game. Validating before you send is the single highest-leverage thing you can do to win it.
Delivery Rate Thresholds and Domain Blocking
A domain's bounce and complaint rate determines whether mailbox providers accept further mail from that domain, including transactional messages. This guide covers the thresholds, the blocking mechanism, and the sources of the underlying data.
Documentation
API Reference: The /validate Endpoint
Everything you need to integrate: the request, the headers, the response shape, and what each status code means.
Authentication & API Keys
How keys work, where to create them, and how to keep public and server-side keys separate and safe.
Integration Examples: cURL, Node.js, Web, and PHP
Working examples of a request to the /validate endpoint in five environments: cURL, Node.js with CommonJS, Node.js with TypeScript, browser JavaScript, and PHP.