Result Codes
Last Updated: August 10, 2026
| Text Code | Numeric Code | Description | OK to send? |
|---|---|---|---|
| Valid | 0 | Verified as real address | Yes |
| Invalid | 1 | Verified as not valid | No |
| Disposable | 2 | A temporary, disposable address | No |
| Accept all (Unverifiable) | 3 | A domain-wide setting (learn more) | Use caution See guidance below |
| Unknown | 4 | The server cannot be reached | Use caution - re-verify first |
Valid
A valid email address has been verified as a real email that is currently accepting mail.
SAFE – These emails exist and have been verified for safe sending.
Invalid
An invalid email address has been verified as a bad recipient address that does not exist or is not accepting mail. Invalid emails will result in a bounce.
DON’T SEND – These emails do not exist and are not safe for sending.
Disposable
Disposable emails are temporary accounts used to avoid using a real personal account during a sign-up process. Common providers of disposable emails include Mailinator, Guerilla Mail, AirMail, and 10 Minute Mail.
DON’T SEND – These emails are fake or temporary emails and are not safe for sending.
Accept All (Unverifiable)
Accept-all (catch-all) is a setting on the recipient's mail server, not a verdict on the individual address — these emails are often valid. As a rule of thumb, catch-alls bounce at about half your list's invalid rate.
An accept all address is commonly used in small businesses to ensure a company receives any email that has been sent to them, regardless of typos. Additionally, these are also found in larger government, medical and educational organizations. Oftentimes these are infact valid emails. However some organizations may utilize this setting as a security feature to prevent unsolicited emails.
SAFE – If you have a dedicated email server with your own IPs, accept all emails may be safe for sending dependent on the overall health of your list.
PROCEED WITH CAUTION – If you use a third-party email provider that requires a bounce rate below 4%, send to accept-all emails selectively rather than excluding them outright: prioritize addresses from a trusted, continuously verified source, send in small segmented batches, and monitor bounce rates as you scale.
Still want to learn more about Accept Alls?
Unknown
Unknown means the mail server didn't give a definitive answer in time (often greylisting or security gateways) — it is not a negative result. Re-verifying later typically returns a definitive result.
SAFE – If you have a dedicated email server with your own IPs, unknown emails are normally safe for sending.
PROCEED WITH CAUTION –If you use a third-party email provider that requires a bounce rate below 4%, re-verify unknowns before sending and treat the remainder like accept-all: source-trusted, segmented, bounce-monitored.