SmtpStatusCode enumeration

Smtp status codes

public enum SmtpStatusCode


Name Value Description
NotDefined 0 Not defined
GeneralFailure -1 General failure
SystemStatus 211 System status, or system help reply. A SMTP status 211 is a message that gives details about the Mail Server status. In the case of a System Help reply, it is a message to the user requesting help information.
HelpMessage 214 A help message for a human reader will follow. SMTP 214 is usually provided as a response to the “HELP” command. A user will usually receive this as a displays of information about the mail server and it will most likely be in the form of a link to the FAQ page of THAT particular SMTP software that is running on the mail server. Due to the nature of this error and how the email server responds, it is normally called a reply, as in SMTP Reply 214.
ServiceReady 220 SMTP Service ready.
ServiceClosingTransmissionChannel 221 Service closing transmission channel
AuthenticationSucceeded 235 Authentication Succeeded
Ok 250 Requested action taken and completed.
UserNotLocalWillForward 251 The recipient is not local to the server, but the server will accept and forward the message.
CannotVerifyUserWillAttemptDelivery 252 The recipient cannot be VRFYed, but the server accepts the message and attempts delivery.
Base64Response 334 Text part containing the [BASE64] encoded string
StartMailInput 354 Start message input and end with. This indicates that the server is ready to accept the message itself
ServiceNotAvailable 421 The service is not available and the connection will be closed.
PasswordTransitionNeeded 432 A password transition is needed
MailboxBusy 450 The requested command failed because the user’s mailbox was unavailable (such as being full). Try again later.
LocalErrorInProcessing 451 The command has been aborted due to a server error. (on their side)
InsufficientStorage 452 The command has been aborted because the server has insufficient system storage.
ClientNotPermitted 454 Client does not have permission. TLS not available due to temporary reason. Encryption required for requested authentication mechanism.
CommandUnrecognized 500 The server could not recognize the command due to a syntax error.
SyntaxError 501 A syntax error was encountered in command arguments.
CommandNotImplemented 502 This command is not implemented.
CommandNotPermitted 503 Сommand is not permitted during a mail transaction
UnrecognizedAuthenticationType 504 Unrecognized authentication type
AuthenticationRequired 530 The SMTP server requires a secure connection or the client was not authenticated. But sometimes it’s about the recipient’s server blacklisting yours, or an invalid email address.
AuthenticationMechanismIsToWeak 534 Authentication mechanism is to weak
CredentialsInvalid 535 Authentication credentials invalid
EncryptionRequiredRequestedMechanism 538 Encryption required for requested authentication mechanism
MailboxUnavailable 550 It usually defines a non-existent email address on the remote side.
UserNotLocalTryAlternatePath 551 “User not local or invalid address – Relay denied”. Meaning, if both your address and the recipient’s are not locally hosted by the server, a relay can be interrupted.
ExceededStorageAllocation 552 “Requested mail actions aborted – Exceeded storage allocation”: simply put, the recipient’s mailbox has exceeded its limits.
MailboxNameNotAllowed 553 “Requested action not taken – Mailbox name invalid”. That is, there’s an incorrect email address into the recipients line.
TransactionFailed 554 This means that the transaction has failed. It’s a permanent error and the server will not try to send the message again.

See Also