unverified
The mailbox could not be confirmed
The domain accepts mail and nothing else argued against the address, but the mailbox handshake ran and the server would not say whether this inbox exists, so the verdict is risky rather than a guess at deliverable.
- appears in
- reason
- verdict
- risky
- risk weight
- +10
- credits
- Free, whatever smtp_reason says: an answer the mailbox check could not settle costs nothing and leaves no 7-day repeat marker, so a later lookup of that address is a fresh one; the uncertain probe result is reused for up to 15 minutes (refresh and max_age do not set it aside), then the mailbox is asked again, and the lookup bills 1 credit only once the mailbox is confirmed.
What it means
A probe was sent and came back without a yes or a no: the server deferred the connection (greylisting), went silent (timeout), refused or could not be reached (no_connect, mx_unreachable), or the handshake partner itself was unavailable (provider_unavailable). smtp_reason names which. smtp_checked is false, mailbox_exists is null, and the unverified weight of 10 is added to the risk score.
mailbox_confidence estimates the odds that the specific mailbox exists from the signals already in the answer: DMARC and SPF, the mail provider, the registration age, the shape of the username, and the delivery outcomes every account has reported for the domain, once there are at least five. A relay alias stays at 50 and only a bounce rate of 50% or more or a plus-tag lowers it, because the domain's records describe the relay operator. Confirmed mailboxes answer deliverable, catch-all domains answer catch_all; unverified is the honest state in between.
What to do
Send with care and branch on mailbox_confidence, or re-verify later: an unverified answer is free and leaves no repeat marker, so once its 15-minute probe result has expired the next lookup asks the server again, and a callback_url on the lookup settles the answer automatically after 5 and 20 minutes.
Example response
{
"email": "[email protected]",
"deliverable": "risky",
"reason": "unverified",
"smtp_checked": false,
"smtp_reason": "greylisted",
"mailbox_exists": null,
"mailbox_confidence": 62
}Abbreviated: a real answer carries all 46 fields, listed in the verify-email reference.
Related
- likely_typo · the domain is a known misspelling of a real mail provider
- parked_domain · the domain is parked or for sale, and still accepts mail
- disposable · the domain belongs to a disposable, temporary email provider
- mx_blocklisted · the domain's mail is served from a network on the threat blocklists
- implicit_mx · the domain has no MX record and relies on the address-record fallback
- mailbox_full · the mailbox is over its storage quota
- no_reply · a no-reply address: mail to it is discarded by design
- role · a shared role inbox such as info@ or support@ rather than a person
- recycled_mailbox · the mailbox exists now, but once answered that it did not
- catch_all · the server accepts every address at the domain, so the mailbox cannot be confirmed
- unverified · signal · the mailbox could not be confirmed (+10)
- All verdict reasons
- Verdicts and the risk score
- API reference
markdown version: /docs/reasons/unverified.md