C＃
Smtp mailer = new Smtp();
mailer.DeliveryNotification.NotifyCondition = DsnNotifyCondition.Always;

VB.NET
Dim mailer As New Smtp() 
mailer.DeliveryNotification.NotifyCondition = DsnNotifyCondition.Always

C＃
mailer.DeliveryNotification.ReturnPortion = DsnReturnPortion.Header;

VB.NET
mailer.DeliveryNotification.ReturnPortion = DsnReturnPortion.Header

?C＃
mailer.DeliveryNotification.TrackingID = "UNQIUE_STRING_q8sdf74d";
VB.NET
mailer.DeliveryNotification.TrackingID = "UNQIUE_STRING_q8sdf74d"

C＃
if (mailer.GetExtension("DSN") != null)
{
    Console.WriteLine("The message will be submitted with DSN support");
}
else
{
    Console.WriteLine("The message will be submitted without DSN support";);
}

VB.NET
If mailer.GetExtension("DSN") IsNot Nothing Then
    Console.WriteLine("The message will be submitted with DSN support")
Else
    Console.WriteLine("The message will be submitted without DSN support")
End If

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

msg.LoadMessage(@"C:\Temp\MyMail.eml");

msg.ConfirmReceipt = "jdoe@domain.com";

VB.NET
' Create new MailMessage object.
Dim msg As New MailMessage()
 
msg.LoadMessage("C:\Temp\MyMail.eml")
 
msg.ConfirmReceipt = "jdoe@domain.com"

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

// Load the message from .eml file
msg.LoadMessage(@"C:\Temp\MyMail.eml");

// Show the e-mail address of recipient of the read confirmation message.
Console.WriteLine("Send confirmation to " + msg.ConfirmRead);

VB.NET
' Create new MailMessage object.
Dim msg As New MailMessage()
 
' Load the message from .eml file
msg.LoadMessage("C:\Temp\MyMail.eml")
 
' Show the e-mail address of recipient of the read confirmation message.
Console.WriteLine("Send confirmation to " + msg.ConfirmRead)