c#中使用REST的带有附件的图形应用编程接口SendMail示例

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

public class SendMailExample
{
    public static async Task SendMailWithAttachment(string apiUrl, string apiKey, string from, string to, string subject, string body, string attachmentPath)
    {
        using (var client = new HttpClient())
        {
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);

            var formData = new MultipartFormDataContent();
            formData.Add(new StringContent(from), "from");
            formData.Add(new StringContent(to), "to");
            formData.Add(new StringContent(subject), "subject");
            formData.Add(new StringContent(body), "body");

            var fileContent = new ByteArrayContent(System.IO.File.ReadAllBytes(attachmentPath));
            fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
            {
                FileName = System.IO.Path.GetFileName(attachmentPath)
            };
            formData.Add(fileContent);

            var response = await client.PostAsync(apiUrl, formData);
            response.EnsureSuccessStatusCode();
        }
    }
}