C#
// Create SMTP object
Smtp mailer = new Smtp();

// Set the message fields.
mailer.From.AsString = "jdoe@domain.com";
mailer.To.AsString = "bill@domain2.com";
mailer.Subject = "Hi";
mailer.BodyPlainText = "This is test message";

// Starts logging SMTP activities into a file. 
mailer.Log.Enabled = true;
mailer.Log.Filename = @"C:\log.txt";
mailer.Log.Clear();

// Specify the server to use. If your server does not require authentication, 
// just omit both last parameters.
mailer.SmtpServers.Add("mail.domain.com", "jdoe", "secret");

// Attempt to connect.
mailer.Connect();

// Display the host name of the server the connection was established with.
Console.WriteLine("Connected to " + mailer.SmtpServers[mailer.GetCurrentSmtpServerIndex()].Name);

// Make sure all the recipients are ok.
if (mailer.TestSend(SendFailureThreshold.AllRecipientsFailed) != TestSendResult.OK)
{
        Console.WriteLine("No recipients can receive the message.");
}// Show refused recipients if any
else if (mailer.GetRefusedRecipients().Count > 0)
{
    Console.WriteLine("The following recipients failed: " + mailer.GetRefusedRecipients().ToString());
}
else
{
    Console.WriteLine("All recipients are ok. Will send the message now.");

    // Send e-mail. If it cannot be delivered, bounce will
    // arrive to bounce@domain3.com, not to joe@domain1.com
    mailer.Send("bounce@domain.com", (string)null);
    Console.WriteLine("Sent to: " + mailer.GetAcceptedRecipients().ToString());
}

// Disconnect from the server
mailer.Disconnect();

VB.NET
' Create SMTP object
Dim mailer As New Smtp

' Set the message fields.
mailer.From.AsString = "jdoe@domain.com"
mailer.To.AsString = "bill@domain2.com"
mailer.Subject = "Hi"
mailer.BodyPlainText = "This is test message"

' Starts logging SMTP activities into a file. 
mailer.Log.Enabled = True
mailer.Log.Filename = "C:\log.txt"
mailer.Log.Clear()

' Specify the server to use. If your server does not require authentication, 
' just remove last 2 parameters.
mailer.SmtpServers.Add("mail.domain.com", "jdoe", "secret")

' Attempt to connect.
mailer.Connect()

' Display the host name of the server the connection was established with.
Console.WriteLine("Connected to " + mailer.SmtpServers(mailer.GetCurrentSmtpServerIndex()).Name)

' Make sure all the recipients are ok.
If mailer.TestSend(SendFailureThreshold.AllRecipientsFailed) <> TestSendResult.OK Then
        Console.WriteLine("No recipients can receive the message.")
Else
    ' Show refused recipients if any
    If mailer.GetRefusedRecipients().Count > 0 Then
        Console.WriteLine("The following recipients failed: " & mailer.GetRefusedRecipients().ToString())
    Else
        Console.WriteLine("All recipients are ok. Will send the message now.")

        ' Send e-mail. If it cannot be delivered, bounce will
        ' arrive to bounce@domain3.com, not to joe@domain1.com
        mailer.Send("bounce@domain.com", CType(Nothing, String))
        Console.WriteLine("Sent to: " + mailer.GetAcceptedRecipients().ToString())
    End If
End If

' Disconnect from the server
mailer.Disconnect()

C＃
// Create a MailMessage object.
MailMessage msg = new MailMessage();

// Add a header.
msg.Headers.Add("MyHeader", "Some value for my own header", false);

VB.NET
' Create a MailMessage object.
Dim msg As New MailMessage()

' Add a header.
msg.Headers.Add("MyHeader", "Some value for my own header", False)

C＃
// Remove the non-standard headers from the message.
msg.Headers.RemoveCustomHeaders();

VB.NET
' Remove the non-standard headers from the message.
msg.Headers.RemoveCustomHeaders()

C＃
// Remove the specified header.
msg.Headers.Remove("X-Special-Header"); 

// Remove the first header.
msg.Headers.RemoveAt(0);

VB.NET
' Remove the specified header.
msg.Headers.Remove("X-Special-Header") 

' Remove the first header.
msg.Headers.RemoveAt(0)