Sending email in C# using Smtp API

using System.Text;
using System.Text.Json;

public class Program
{
    public static async Task Main(string[] args)
    {
        var consumerKey = "<CONSUMER_KEY>";
        var consumerSecret = "<CONSUMER_SECRET>";

        string url = "https://api.turbo-smtp.com/api/v2/mail/send";
        
        var mailData = new { 
            from = "hello@your-company.com", 
            to = "Doe.Jhon@gmail.com,contact@global-travel.com",
            subject = "New live training session",
            cc = "cc_user@example.com",
            bcc = "bcc_user@example.com",
            content = "Dear partner, we are delighted to invite you to an exclusive training session on UX Design. This session is designed to provide essential insights and practical strategies to enhance your skills.",
            html_content = "Dear partner, We are delighted to invite you to an exclusive training session on <strong>UX Design</strong>. This session is designed to provide essential insights and practical strategies to enhance your skills."
        }; // Mail Data setup.

        using (HttpClient httpClient = new HttpClient())
        {
            // JSON data seriaization
            var json = JsonSerializer.Serialize(mailData);
            var content = new StringContent(json, Encoding.UTF8, "application/json");

            // Set authentication headers
            content.Headers.Add("consumerKey", consumerKey);
            content.Headers.Add("consumerSecret", consumerSecret);

            // Trigger POST request
            using (var response = await httpClient.PostAsync(url, content))
            {
                if (response.IsSuccessStatusCode)
                {
                    var result = await response.Content.ReadAsStringAsync();
                    Console.WriteLine("Response: " + result);
                }
                else
                {
                    Console.WriteLine("Request error: " + response.StatusCode);
                }
            }
        }
    }
}