email address exists checker api
Email address exists checker API
Use an address-exists checker when you want a simple API wrapper around DNS and SMTP signals.
The API should return a clear result your application can store and act on.
It is useful for onboarding, imports, and fraud reduction.
It should provide response codes that are easy to map into UI states.
{
"result": "risky",
"score": 64,
"signals": ["mx_found", "free_email", "catch_all"]
}What is returned?
Usually a result, score, and a few signal flags that explain the decision.
Where should I use it?
Use it in backends, jobs, and API validation layers rather than in browser code.
What SMTP probing actually proves
SMTP probing is a protocol conversation with the recipient domain. It can indicate whether a mailbox appears to accept mail, but it also reflects server policy, temporary throttling, anti-abuse behavior, and catch-all handling.
How to use it safely
Keep probing on the server, add timeouts, respect provider limits, and avoid repeated retries against the same domain. In production, you should store only the resulting status and score, not the full transcript.
FAQ
How do I use this page?
Use it as a quickstart reference and link it from your docs, onboarding flow, or marketing page.
What should I do next?
Create an account, try the demo, and move the integration into your backend with a real API key.
Can SMTP confirm the owner is real?
No. It only suggests that the mailbox path looks reachable at the time of the check.
Why not send a message instead?
Because many products need a quiet validation path before onboarding or import completes.