Understanding Result Statuses
Every verified email receives one of four status labels. Understanding these helps you decide which addresses to include in campaigns.
SafeDeliverable — send freely
The email passed all checks: valid syntax, working MX record, and the SMTP server confirmed the mailbox exists. This is the gold standard for email deliverability.
RiskyValid but uncertain — send with caution
An email is marked risky when one or more of these conditions apply:
- Disposable email domain (e.g. mailinator.com, guerrillamail.com)
- Catch-all domain — the server accepts all addresses, including non-existent ones
- Known spamtrap or honeypot pattern
- Deferred verification gateway (e.g. Microsoft 365, Google Workspace) — SMTP always returns OK
- Suspicious local-part (all digits, very long, fake pattern like "test123")
InvalidDo not send
Confirmed as non-deliverable. Causes include:
- Malformed syntax (missing @, invalid characters, TLD missing)
- Domain has no MX record or is a parked/inactive domain
- Domain typo detected (e.g. gmial.com)
- SMTP server explicitly rejected the recipient (550, 551, 553)
- Mailbox does not exist
UnknownCould not verify — retry or skip
The domain has valid MX records but the SMTP server was unreachable (connection timeout, port 25 blocked by your network, IP temporarily rate-limited). Unknown results are not cached — re-running verification will attempt a fresh SMTP check.
Recommended sending strategy
| Status | Include in campaign? | Notes |
|---|---|---|
| Safe | ✓ Yes | Always safe to include |
| Risky | Conditional | Include only if list is small or you accept a lower deliverability rate |
| Invalid | ✗ Never | Will hard-bounce and damage sender reputation |
| Unknown | Optional | Re-verify first; if still unknown, skip to be safe |