SmtpStatusCode Enumeration

Specifies the outcome of sending e-mail by using the SmtpClient class.

Namespace: System.Net.Mail
Assembly: System (in system.dll)

public enum SmtpStatusCode
public enum SmtpStatusCode
public enum SmtpStatusCode

 Member nameDescription
BadCommandSequenceThe commands were sent in the incorrect sequence. 
CannotVerifyUserWillAttemptDeliveryThe specified user is not local, but the receiving SMTP service accepted the message and attempted to deliver it. This status code is defined in RFC 1123, which is available at
ClientNotPermittedThe client was not authenticated or is not allowed to send mail using the specified SMTP host. 
CommandNotImplementedThe SMTP service does not implement the specified command. 
CommandParameterNotImplementedThe SMTP service does not implement the specified command parameter. 
CommandUnrecognizedThe SMTP service does not recognize the specified command. 
ExceededStorageAllocationThe message is too large to be stored in the destination mailbox. 
GeneralFailureThe transaction could not occur. You receive this error when the specified SMTP host cannot be found. 
HelpMessageA Help message was returned by the service. 
InsufficientStorageThe SMTP service does not have sufficient storage to complete the request. 
LocalErrorInProcessingThe SMTP service cannot complete the request. This error can occur if the client's IP address cannot be resolved (that is, a reverse lookup failed). You can also receive this error if the client domain has been identified as an open relay or source for unsolicited e-mail (spam). For details, see RFC 2505, which is available at
MailboxBusyThe destination mailbox is in use. 
MailboxNameNotAllowedThe syntax used to specify the destination mailbox is incorrect. 
MailboxUnavailableThe destination mailbox was not found or could not be accessed. 
MustIssueStartTlsFirstThe SMTP server is configured to accept only TLS connections, and the SMTP client is attempting to connect by using a non-TLS connection. The solution is for the user to set EnableSsl=true on the SMTP Client. 
OkThe email was successfully sent to the SMTP service. 
ServiceClosingTransmissionChannelThe SMTP service is closing the transmission channel. 
ServiceNotAvailableThe SMTP service is not available; the server is closing the transmission channel. 
ServiceReadyThe SMTP service is ready. 
StartMailInputThe SMTP service is ready to receive the e-mail content. 
SyntaxErrorThe syntax used to specify a command or parameter is incorrect. 
SystemStatusA system status or system Help reply. 
TransactionFailedThe transaction failed. 
UserNotLocalTryAlternatePathThe user mailbox is not located on the receiving server. You should resend using the supplied address information. 
UserNotLocalWillForwardThe user mailbox is not located on the receiving server; the server forwards the e-mail. 

The values in the SmtpStatusCode enumeration specify reply status values sent by a Simple Mail Transfer Protocol (SMTP) server. The SmtpException and SmtpFailedRecipientsException classes contain StatusCode properties that return SmtpStatusCode values.

SMTP is defined in RFC 2821 available at

The following code example displays an error message to the console when an SmtpException is thrown.

public static void CreateMessageWithAttachment3(string server, string to)
    // Specify the file to be attached and sent.
    // This example assumes that a file named Data.xls exists in the
    // current working directory.
    string file = "data.xls";
    // Create a message and set up the recipients.
    MailMessage message = new MailMessage(
       "Quarterly data report",
       "See the attached spreadsheet.");

    // Create  the file attachment for this e-mail message.
    Attachment data = new Attachment("Qtr3.xls");
    // Add time stamp information for the file.
    ContentDisposition disposition = data.ContentDisposition;
    disposition.CreationDate = System.IO.File.GetCreationTime(file);
    disposition.ModificationDate = System.IO.File.GetLastWriteTime(file);
    disposition.ReadDate = System.IO.File.GetLastAccessTime(file);
    // Add the file attachment to this e-mail message.
    //Send the message.
    SmtpClient client = new SmtpClient(server);
    // Add credentials if the SMTP server requires them.
    client.Credentials = (ICredentialsByHost)CredentialCache.DefaultNetworkCredentials;
    // Notify user if an error occurs.
    catch (SmtpException e)
        Console.WriteLine("Error: {0}", e.StatusCode);

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0