Assembly: System (in System.dll)
You cannot change the value of this property when an e-mail is being sent.
Some SMTP servers require that the client be authenticated before the server sends e-mail on its behalf. Set this property to true when this SmtpClient object should, if requested by the server, authenticate using the default credentials of the currently logged on user. For client applications, this is the desired behavior in most scenarios.
Credentials information can also be specified using the application and machine configuration files. For more information, see <mailSettings> Element (Network Settings).
If the property is set to false, then the value set in the Credentials property will be used for the credentials when connecting to the server. If the property is set to false and the Credentials property has not been set, then mail is sent to the server anonymously.
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.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.