The following code is developed in VB:
Sub Button1_Click(sender As Object, e As EventArgs)
' Build a MailMessage
Dim mailMessage As System.Web.Mail.MailMessage = New System.Web.Mail.MailMessage
mailMessage.From = "from_email@domain.com"
mailMessage.To = "to_email@domain.com"
mailMessage.Subject = "Email Subject"
mailMessage.Body = "EMail Message Body"
mailMessage.BodyFormat = System.Web.Mail.MailFormat.Html
'Authentication
mailMessage.Fields("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = 25
mailMessage.Fields("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2
mailMessage.Fields("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") = 1
mailMessage.Fields("http://schemas.microsoft.com/cdo/configuration/sendusername") = "user@domain.com"
mailMessage.Fields("http://schemas.microsoft.com/cdo/configuration/sendpassword") = "password"
System.Web.Mail.SmtpMail.SmtpServer = "mail.domain.com"
System.Web.Mail.SmtpMail.Send(mailMessage)
End Sub