Question 1

Why do I get risky or unknown instead of valid?

Accepted Answer

Because we only say deliverable when a live SMTP check proved the mailbox exists. Catch-all domains accept every address, and providers such as Outlook and Yahoo never reveal whether a mailbox exists. Instead of guessing, we return risky or unknown with a machine-readable reason, so you can decide how to treat those addresses.

Question 2

Does the check send an email to the address?

Accepted Answer

No. The SMTP dialogue stops before any message is transmitted: we ask the recipient's server whether it would accept the address and disconnect. Nothing lands in the inbox.

Question 3

How is the batch endpoint billed?

Accepted Answer

One verification per address in the submitted list. Fetching batch results and the health endpoint are free.

Email Verification with Live SMTP Proof

Frequently Asked Questions