"ok" - all is ok, The server is saying that it’s ready to receive a letter to this address and no tricks are detected.

"error" - server is saying that delivery was failed, but no information about email existence or availability.

"smtp_error" - an answer of the SMTP server is invalid or the server is responding with some internal error.

"smtp_protocol" - SMTP server allows us to connect, but closing SMTP session before email was verified.

"unknown_email" - server is saying that the delivery was failed and email does not exist.

"attempt_rejected" - delivery fail, reason similar to "rejected".

"relay_error" - delivery fails because of some relaying problem.

"antispam_system" - some anti-spam technology is blocking the verification process.

"email_disabled" - email account is suspended/disabled/limited and can't receive emails.

"domain_error" - email server or DNS for whole domain is not installed or incorrect, so all emails are not deliverable.

"ok_for_all" - email server is saying that it’s ready to accept a letter to any email.

"dead_server" - email server is dead, no connection to it.

"syntax_error" - syntax error in email address.

"unknown" - This often happens if the destination mail server is too slow or temporarily unavailable. In some cases, retrying your request after about 5-15 minutes will return a valid or invalid response.

"not_validated" - means this email was not yet verified in LeadRocks. You should initiate this process again. Read more about the verification process here: https://help.leadrocks.io/en/articles/6280893-email-list-verification-how-it-works