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SmtpClient.Credentials Property

Gets or sets the credentials used to authenticate the sender.

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

'Declaration
Public Property Credentials As ICredentialsByHost
	Get
	Set

Property Value

Type: System.Net.ICredentialsByHost
An ICredentialsByHost that represents the credentials to use for authentication; or Nothing if no credentials have been specified.

ExceptionCondition
InvalidOperationException

You cannot change the value of this property when an email is being sent.

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 UseDefaultCredentials to true instead of setting this property. 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.

Credentials information can also be specified using the application and machine configuration files. For more information, see <mailSettings> Element (Network Settings). If information is specified using the Credentials property, this information overrides the configuration file settings.

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 setting the credentials used to send an e-mail.


Public Shared Sub CreateTestMessage1(ByVal server As String, ByVal port As Integer)
    Dim [to] As String = "jane@contoso.com"
    Dim [from] As String = "ben@contoso.com"
    Dim subject As String = "Using the new SMTP client."
    Dim body As String = "Using this new feature, you can send an e-mail message from an application very easily."
    Dim message As New MailMessage([from], [to], subject, body)
    Dim client As New SmtpClient(server, port)
    ' Credentials are necessary if the server requires the client 
    ' to authenticate before it will send e-mail on the client's behalf.
    client.Credentials = CredentialCache.DefaultNetworkCredentials

    Try
        client.Send(message)
    Catch ex As Exception
        Console.WriteLine("Exception caught in CreateTestMessage1(): {0}", ex.ToString())
    End Try
End Sub


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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