static public bool SendMail(string mittente, string destinatario, string oggetto, string corpo)
    {
        bool res = true;

        corpo = Formattazione.PulisciDocumento(corpo);
        try
        {
            MailMessage msg = new MailMessage();
            msg.From = new MailAddress(mittente, mittente);
            string[] destinatari = destinatario.Replace(",", ";").Split(char.Parse(";"));
            foreach (string to in destinatari)
                msg.To.Add(new MailAddress(to, to));
            msg.Subject = oggetto;
            
            //********************* vedi funzione originale sotto, dovrebbe evitare antispam******
            msg.BodyEncoding = System.Text.Encoding.GetEncoding("utf-8");
            System.Net.Mail.AlternateView plainView = System.Net.Mail.AlternateView.CreateAlternateViewFromString
            (System.Text.RegularExpressions.Regex.Replace(corpo, @"<(.|\n)*?>", string.Empty), null, "text/plain");
            System.Net.Mail.AlternateView htmlView = System.Net.Mail.AlternateView.CreateAlternateViewFromString(corpo, null, "text/html");
            msg.AlternateViews.Add(plainView);
            msg.AlternateViews.Add(htmlView);
            msg.IsBodyHtml = true; //300316
            msg.Priority = MailPriority.High; //300316
            //************************************************************************************/

            SmtpClient smtpClient = new SmtpClient();            

            smtpClient.Send(msg);
        }
        catch (SmtpException smtpException)
        {
            res = false;
        }
        catch (Exception ex)
        {
            res = false;
        }

        return res;
    }

<system.net>
    <mailSettings>
      <smtp deliveryMethod="Network" from="noreply@xxx.com">
        <network host="smtp.aruba.it" userName="noreply@xxx.com" password="xxx" port="25" />
      </smtp>
    </mailSettings>
  </system.net>

<mailSettings>
      <smtp from="noreply@xxx.com">
        <network host="smtps.aruba.it" userName="noreply@xxx.com" password="xxx" port="465" enableSsl="true" defaultCredentials="false" />
      </smtp>
    </mailSettings>