The following example demonstrates sending your username and password to the SMTP server to provide authentication.

[ C# ]
private void Page_Load(object sender, System.EventArgs e)
{
MailMessage mail = new MailMessage();
mail.To = "me@mycompany.com";
mail.From = "you@yourcompany.com";
mail.Subject = "this is a test email.";
mail.Body = "Some text goes here";
mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1"); //basic authentication
mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", "my_username_here"); //set your username here
mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", "super_secret"); //set your password here SmtpMail.SmtpServer = "mail.mycompany.com"; //your real server goes here
SmtpMail.Send( mail );
}

[ VB.NET ]
Private Sub Page_Load(sender As Object, e As System.EventArgs)
Dim mail As New MailMessage()
mail.To = "me@mycompany.com"
mail.From = "you@yourcompany.com"
mail.Subject = "this is a test email."
mail.Body = "Some text goes here"
mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1") 'basic authentication
mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", "my_username_here") 'set your username here
mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", "super_secret") 'set your password here
SmtpMail.SmtpServer = "mail.mycompany.com" 'your real server goes here
SmtpMail.Send(mail)