How to send automatic email confirmation in .net?

    Private Sub sendadminEmail()
        Try
            Dim ToAddress As String = ConfigurationManager.AppSettings("AdminEmail")
            Dim mm As New MailMessage(emailTextbox.Text, ToAddress)
            mm.Subject = _Subject
            mm.Body = _Body
            mm.IsBodyHtml = False
            Dim smtp As New SmtpClient
            
            smtp.Send(mm)
        Catch ex As Exception
            LogWriter(ex.Message)
        End Try
    End Sub