使用 OAuth 認證存取 Office 365 雲端 Exhange 收發信

{
    "resourceAppId": "00000002-0000-0ff1-ce00-000000000000",
    "resourceAccess": [
        {
            "id": "dc890d15-9560-4a4c-9b7f-a736ec74ec40",
            "type": "Role"
        }
    ]
}

using Microsoft.Exchange.WebServices.Data;
using Microsoft.Identity.Client;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;

namespace RcvAndSendMail
{
    class Program
    {
        static ExchangeService InitEws()
        {
            // 取得 Token
            var cca = ConfidentialClientApplicationBuilder
                .Create(AppConstants.AppId)
                .WithClientSecret(AppConstants.ClientSecret)
                .WithTenantId(AppConstants.TenantId)
                .Build();
            var ewsScopes = new string[] { "https://outlook.office365.com/.default" };
            var authResult = cca.AcquireTokenForClient(ewsScopes).ExecuteAsync().Result;

            var ews = new ExchangeService(ExchangeVersion.Exchange2013_SP1);
            ews.Url = new Uri("https://outlook.office365.com/ews/exchange.asmx");

            //企業地端Exchange比較簡單，可傳入帳密登入
            //ews.Credentials  = new NetworkCredential(userName, password, domain);
            //或使用執行程式的AD帳號自動登入
            //ews.UseDefaultCredentials = true;

            //Office 365 登入方式
            ews.Credentials = new OAuthCredentials(authResult.AccessToken);
            //ews.TraceEnabled = true;
            ews.ImpersonatedUserId = new ImpersonatedUserId(
                ConnectingIdType.SmtpAddress, AppConstants.Email);
            
            return ews;
        }

        static void Main(string[] args)
        {
            var ews = InitEws();
            CheckInbox(ews);
            SendEmail(ews);
            Console.ReadLine();
        }

        static void CheckInbox(ExchangeService ews)
        {
            
            //https://docs.microsoft.com/en-us/exchange/client-developer/exchange-web-services/how-to-work-with-exchange-mailbox-items-by-using-ews-in-exchange
            // 繫結到收件匣
            Folder inbox = Folder.Bind(ews, WellKnownFolderName.Inbox);
            // 篩選未讀信件
            SearchFilter sf = new SearchFilter.SearchFilterCollection(LogicalOperator.And, 
                new SearchFilter.IsEqualTo(EmailMessageSchema.IsRead, false));

            ItemView view = new ItemView(10);
            // Fire the query for the unread items.
            // This method call results in a FindItem call to EWS.
            FindItemsResults<Item> findResults = ews.FindItems(WellKnownFolderName.Inbox, sf, view);
            foreach (var item in findResults.Items)
            {
                string subject = item.Subject;
                if (item is EmailMessage && subject.StartsWith("#BOT"))
                {
                    //信件內容及附件要 Load() 才會載入
                    item.Load();
                    var mail = item as EmailMessage;
                    var text = mail.Body.Text;
                    Console.WriteLine($"收件時間：{item.DateTimeReceived:yyyy/MM/dd HH:mm}");
                    Console.WriteLine($"寄件者：{mail.From}");
                    Console.WriteLine($"主旨：{item.Subject}");
                    Console.WriteLine($"內容：{text}");
                    //TODO 執行特定作業
                    //刪除有 HardDelete/SoftDelete/MoveToDeletedItems 三種模式
                    item.Delete(DeleteMode.HardDelete);
                }
            }

        }

        static void SendEmail(ExchangeService ews)
        {
            var mail = new EmailMessage(ews);
            mail.ToRecipients.Add(AppConstants.TestRecipient);
            mail.Subject = $"發信測試: {DateTime.Now:HHmmss}";
            mail.Body = new MessageBody(BodyType.Text, "Sent from Office 365");
            mail.Send(); //或是 mail.SendAndSaveCopy();
        }
    }
}