Understanding Results & Provider Limits

Email verification combines syntax, DNS, MX, SMTP response where available, and risk signals. Some mailbox providers intentionally make mailbox-level confirmation impossible, so Kawaa flags those cases instead of presenting them as confirmed mailboxes.

Status Is the Primary Verdict

Status	How to use it
`valid`	Low risk. Use for normal sends, while still honoring unsubscribe and consent rules.
`risky`	Use caution or skip. The address may receive mail, but a risk signal or provider limitation remains.
`unknown`	Do not treat as confirmed. Retry later or use another confirmation signal.
`invalid`	Do not send. The address failed a hard verification check.

Quality Score

The score is a supporting number, not a replacement for status and sub_status. Risky, unknown, catch-all, policy-blocked, greylisted, and connection-failure results are capped so they cannot outrank their caveat.

Catch-All Domains

A catch-all domain accepts mail for many or all local parts. Kawaa marks these as risky or catch_all because SMTP cannot prove whether a specific mailbox belongs to a real user.

Provider Accept-All

Consumer mailbox providers such as Outlook-family domains can accept verification probes for addresses that may not exist. These results are down-ranked and flagged with provider_accept_all.

SDK Booleans

SDK helpers such as isDeliverable are true only when the API status is valid. For automation, also inspect status, sub_status, and verification details before sending.

Recommended Automation

Send normally only for status: valid.
Review, suppress, or confirm by another channel for status: risky.
Retry later for unknown, greylisted, or connection_failure.
Do not treat catch_all or provider_accept_all as mailbox-confirmed.

See the Verification API reference for the full response shape.