System.Net.Mail.SmtpClient.Credentials Property

Gets or sets the credentials used to authenticate the sender.


public System.Net.ICredentialsByHost Credentials { get; set; }


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Some SMTP servers require that the client be authenticated before the server will send e-mail on its behalf. To use your default network credentials, you can set the SmtpClient.UseDefaultCredentials to true instead of setting this property. If the SmtpClient.UseDefaultCredentials property is set to false, then the value set in the SmtpClient.Credentials property will be used for the credentials when connecting to the server. If the SmtpClient.UseDefaultCredentials property is set to false and the SmtpClient.Credentials property has not been set, then mail is sent to the server anonymously.

Credentials information can also be specified using the application and machine configuration files. For more information, see mailSettings for If information is specified using the SmtpClient.Credentials property, this information overrides the configuration file settings.


If you provide credentials for basic authentication, they are sent to the server in clear text. This can present a security issue because your credentials can be seen, and then used by others.


Namespace: System.Net.Mail
Assembly: System (in System.dll)
Assembly Versions:,
Since: .NET 2.0