Adding recipients to the X-SMTPAPI Header with sendgrid-csharp

gistfile1.cs

using System;
using System.Collections.Generic;
using SendGridMail;
using System.Net;
using SendGridMail.Transport;
using System.Net.Mail;

namespace EmailTester
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			// Create the email object first, then add the properties.
			SendGrid myMessage = SendGrid.GetInstance();

			var recipients = new List<string>();

			//You could loop through your dataset here and add each recipient, up to 1000 recipients per message
			recipients.Add("Brandon @ Work <brandon.west@sendgrid.com>");
			recipients.Add("Brandon @ Gmail <brawest@gmail.com>");

			//We want to add the recipients to the X-SMTPAPI header
			myMessage.Header.AddTo(recipients);

			//Even though we added recipients to the Header, the envelope must also have a valid recipient
			myMessage.AddTo("brawest@gmail.com");

			myMessage.From = new MailAddress("brandon@sendgrid.com", "Brandon West");
			myMessage.Subject = "Testing the SendGrid Library";
			myMessage.Text = "Hello World!";

			// Create credentials, specifying your user name and password.
			var credentials = new NetworkCredential("xxxxxxxx", "xxxxxxx");

			// Create an SMTP transport for sending email.
			var transportSMTP = SMTP.GetInstance(credentials);

			// Send the email.
			transportSMTP.Deliver(myMessage);
		}
	}
}

Hello Brandon,

I've been testing X-SMTP API and it works great, but I have a problem with
spanish caracters like á or é when I include them in _substitution values
in header. For instance if I include 'Que día más bueno hace' I receive '_Que
d?a m?s bueno hace'.

SendGrid technical service has told me to use UTF-8 character encoding but I can't see how to do it using your API.

Could you please give any advise for avoiding this?. Thanks in advance.

Regards,

Juan Pablo