• 我已经按照要求试过了，我也面临着你得到的同样的错误。

x1c 0d1x的数据

• 然后，我更新了代码，请检查下面。

using Azure.Identity;
using Microsoft.Graph;
using System;
using System.IO;

namespace GraphApp
{
    class MSGraph
    {
        static async Task Main(string[] args)
        {
            var scopes = new[] { "https://graph.microsoft.com/.default" };
            var tenantId = "tenant_Id";
            var clientId = "client_Id";
            var clientSecret = "client_Secret";
            var options = new TokenCredentialOptions
            {
                AuthorityHost = AzureAuthorityHosts.AzurePublicCloud
            };
            var clientSecretCredential = new ClientSecretCredential(tenantId, clientId, clientSecret, options);
            var graphClient = new GraphServiceClient(clientSecretCredential, scopes);

            try
            {
                var message = await graphClient.Users["User_UPN"]
                    .MailFolders["inbox"]
                    .Messages["message_ID"]
                    .GetAsync();

                var mimeContentStream = await graphClient.Users["User_ID"]
                    .Messages[message.Id]
                    .Content
                    .GetAsync();

                using (var fileStream = File.Create("C:\\Users\\xxxxxxx\\Desktop\\web1\\lastemail.eml"))
                {
                    mimeContentStream.Seek(0, SeekOrigin.Begin);
                    await mimeContentStream.CopyToAsync(fileStream);
                }

                Console.WriteLine("Email message downloaded successfully.");
            }
            catch (ServiceException ex)
            {
                Console.WriteLine($"Error accessing the Graph API: {ex.Message}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"An error occurred: {ex.Message}");
            }
        }
    }
}

字符串

• 当我执行上面的代码时，.eml文件成功下载到下面给定的路径

的

参考文献：

• 引用自Glen Scales -How to Download a Mail | Graph API | C#。