SmtpClient.UseDefaultCredentials Property

Gets or sets a Boolean value that controls whether the DefaultCredentials are sent with requests.

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

public bool UseDefaultCredentials { get; set; }

Property Value

Type: System.Boolean
true if the default credentials are used; otherwise false. The default value is false.

ExceptionCondition
InvalidOperationException

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 UseDefaultCredentials 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 UseDefaultCredentials property is set to false and the Credentials property has not been set, then mail is sent to the server anonymously.

Caution noteCaution

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.

The following code example demonstrates using this property.

		public static void CreateTestMessage2(string server)
		{
			string to = "jane@contoso.com";
			string from = "ben@contoso.com";
			MailMessage message = new MailMessage(from, to);
			message.Subject = "Using the new SMTP client.";
			message.Body = @"Using this new feature, you can send an e-mail message from an application very easily.";
			SmtpClient client = new SmtpClient(server);
			// Credentials are necessary if the server requires the client  
			// to authenticate before it will send e-mail on the client's behalf.
			client.UseDefaultCredentials = true;

      try {
			  client.Send(message);
			}  
			catch (Exception ex) {
			  Console.WriteLine("Exception caught in CreateTestMessage2(): {0}", 
                    ex.ToString() );			  
      }              
		}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

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.

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