How to send mail using C#

string from = "", to = "", smtpServer = "", username = "", password = "", smtpport = "";

          

            smtpServer = ConfigurationSettings.AppSettings["Comment_Mail_SmptHost"];

            from = ConfigurationSettings.AppSettings["Comment_Onbehalf_Mail"];

            to = ConfigurationSettings.AppSettings["Comment_To_Mail"];

            username = ConfigurationSettings.AppSettings["Comment_From_Mail"];

            password = ConfigurationSettings.AppSettings["Comment_From_Password"];

            smtpport = ConfigurationSettings.AppSettings["Comment_Mail_Port"];

            StringBuilder strbuild = new StringBuilder();

            strbuild.Remove(0, strbuild.Length);

            strbuild.Append("Body");

            MailMessage msg = new MailMessage(from, to, "Subject", strbuild.ToString());

            msg.BodyEncoding = Encoding.ASCII;

            msg.IsBodyHtml = true;

            msg.SubjectEncoding = System.Text.Encoding.UTF8;

            msg.Priority = MailPriority.High;

            SmtpClient smtpClt = new SmtpClient(smtpServer, Convert.ToInt32(smtpport));

            smtpClt.Credentials = new NetworkCredential(username, password);

            smtpClt.Send(msg);

Note: when hosting on server change SMTPHost as localhost if it deployed in same server