Status codes of the validation result field and their meanings

Of the fields the validation report includes, the ResultStatus field contains the exact status code returned by the hosted email validation service engine.

The possible values for this field includes the following:

Success

The e-mail address was verified successfully up to the required level. 

UnmatchedQuotedPair

A quoted pair within a quoted word is not closed properly. 

UnexpectedQuotedPairSequence

An unexpected quoted pair sequence has been found within a quoted word. 

InvalidWordBoundaryStart

A new word boundary start has been detected at an invalid position. 

InvalidCharacterInSequence

An invalid character has been detected in the provided sequence. 

UnbalancedCommentParenthesis

The number of parenthesis used to open comments is not equal to the one used to close them. 

DoubleDotSequence

An invalid sequence of two adjacent dots has been found. 

InvalidLocalPartLength

The local part of the e-mail address has an invalid length. 

InvalidFoldingWhiteSpaceSequence

An invalid folding white space (FWS) sequence has been found. 

IspSpecificSyntaxFailure

Email syntax is invalid as per specific requirements for the internet service provider. 

AtSignNotFound

The at sign symbol (@), used to separate the local part from the domain part of the address, has not been found. 

InvalidEmptyQuotedWord

An invalid quoted word with no content has been found. 

InvalidAddressLength

The email address has an invalid total length. 

DomainPartCompliancyFailure

The domain part of the email address is not compliant with the IETF standards. 

DnsQueryTimeout

A timeout has occured while querying the DNS server(s) for records about the e-mail address domain. 

DnsConnectionFailure

Verification failed because of a socket connection error occured while querying the DNS server. 

DomainIsInexistent

The domain of the e-mail address does not exist. 

DomainIsMisconfigured

This failure means that the domain of the email address does not have any valid DNS records and couldn't accept messages from another host on the Internet.

DomainIsWellKnownDea

The e-mail address is provided by a well known disposable e-mail address provider (DEA). 

SmtpConnectionTimeout

A timeout has occurred while connecting to the mail exchanger which serves the e-mail address domain. 

SmtpConnectionFailure

A socket connection error occurred while connecting to the mail exchanger which serves the e-mail address domain. 

SmtpDialogueError

An error occurred while communicating with the mail exchanger which serves the e-mail address domain.

MailboxDoesNotExist

The mailbox for the e-mail address does not exist. 

MailboxConnectionFailure

A connection error occurred while validating the mailbox for the e-mail address. 

LocalSenderAddressRejected

The external mail exchanger rejected the local sender address. 

LocalEndPointRejected

The external mail exchanger rejected the local end point. 

MailboxValidationTimeout

A timeout occured while verifying the existence of the mailbox. 

MailboxTemporarilyUnavailable

The requested mailbox is temporarily unavailable. 

This is not an indicator that the mailbox actually exists but, often, a message sent by external mail exchangers with greylisting enabled. To complete the validation of the address, the system re-process the verification multiple times with small delays (usually 5-10 minutes), until the server answers with a different message or the number of validations hits its limit.

ServerDoesNotSupportInternationalMailboxes

The external mail exchanger does not support international mailbox names. To support this feature, mail exchangers must comply with RFC 5336 and support and announce both the 8BITMIME and the UTF8SMTP protocol extensions. 

CatchAllValidationTimeout

A timeout occured while verifying fake e-mail address rejection for the mail server. 

ServerIsCatchAll

The external mail exchanger accepts fake, non existent, e-mail addresses; therefore the provided e-mail address MAY be inexistent too. 

CatchAllConnectionFailure

A connection error occurred while verifying the external mail exchanger rejects inexistent e-mail addresses. 

ProxyConnectionTimeout

A timeout occured while connecting to the configured proxy server. 

HttpConnectionTimeout

A timeout has occured while connecting to the HTTP server (webmail) which serves the e-mail address domain. 

HttpConnectionFailure

A socket connection error occured while connecting to the HTTP server (webmail) which serves the e-mail address domain. 

UnhandledException

One or more unhandled exceptions have been thrown during the verification process.



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