smtp email verification api
SMTP email verification API
Use SMTP probing when you need stronger mailbox signals than MX alone.
SMTP probing can reveal whether a mailbox accepts RCPT TO commands.
It is useful for high-value signups and tighter list hygiene.
It should be rate-limited because SMTP servers can be sensitive to abuse.
220 mail.example.com ESMTP
EHLO emailverify.se
MAIL FROM:<[email protected]>
RCPT TO:<[email protected]>
QUITHow it works
The service opens a short SMTP session and checks whether the mailbox appears reachable.
When to use it
Use it after syntax, MX, and disposable checks have already passed.
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.