C#格式的SendGrid CORS响应

using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        using (HttpClient client = new HttpClient())
        {
            // 设置请求头，允许跨域访问
            client.DefaultRequestHeaders.Add("Access-Control-Allow-Origin", "*");

            // 发送HTTP请求
            HttpResponseMessage response = await client.GetAsync("https://api.sendgrid.com/v3/mail/send");

            // 处理响应
            if (response.IsSuccessStatusCode)
            {
                // 响应成功
                string responseBody = await response.Content.ReadAsStringAsync();
                Console.WriteLine("响应内容：" + responseBody);
            }
            else
            {
                // 响应失败
                Console.WriteLine("响应失败，状态码：" + response.StatusCode);
            }
        }
    }
}