TestSending.cs

using System.Net.Mail;
using System.Net;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;

public class TestClass {
  public static void Main() {
      string subject = "";
      string body = "";
      string host = "smtp.hubapi.com";
      string username = "";
      string password = "";
      string recipientAddress = "some address";
      string recipientName = "some name";
      string fromAddress = "some address";

      SmtpClient client;
      MailMessage mail;

      // Always validate the remote certificate chain
      ServicePointManager.ServerCertificateValidationCallback =
                delegate(object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
                    { return true; };

      client = new SmtpClient(host, 587);
      NetworkCredential basicCredential = new NetworkCredential(username, password);

      client.UseDefaultCredentials = false;
      client.Credentials = basicCredential;
      client.EnableSsl = true;

      mail = new MailMessage();
      mail.From = new MailAddress(fromAddress);
      foreach (string recipient in recipientAddress.Split(','))
          {
              mail.To.Add(new MailAddress(recipient, recipientName));
          }

      /*
      if (msPdf != null)
          {
              msPdf.Position = 0;
              Attachment attachment = new Attachment(msPdf, pdfName, "application/pdf");
              mail.Attachments.Add(attachment);
          }
      */

      mail.Subject = subject;
      mail.IsBodyHtml = true;
      mail.Body = body;
      client.Send(mail);
  }
}