Send Mail via Microsoft Graph using MIMEKit, Graph SDK and MSAL

gistfile1.txt

using System;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.Http;
using System.Net.Http.Headers;
using Microsoft.Identity.Client;
using Newtonsoft.Json;
using Microsoft.Graph;
using System.IO;
using MimeKit;
using MimeKit.Utils;

namespace GraphMimeKitMSAL
{
	class Program
	{
		static void Main(string[] args)
		{
			string mailboxName = "user@domain.com";
			String recipient = "target@domain.com";
			string scope = "https://graph.microsoft.com/.default";
			string redirectUri = "http://localhost";
			string clientId = "5471030d-f311-4c5d-91ef-74ca885463a7";
			string inlineImagePath = @"C:\temp\test.jpg";
			// Code attribution
                        // The following MIMEkit code is a modified version of the sample included on
			// http://www.mimekit.net/docs/html/Working-With-Messages.htm
			var message = new MimeMessage();
			message.From.Add(MailboxAddress.Parse(mailboxName));
			message.To.Add(MailboxAddress.Parse(recipient));
			message.Subject = "How you doin?";

			// create our message text, just like before (except don't set it as the message.Body)

			var builder = new BodyBuilder();

			// Set the plain-text version of the message text
			builder.TextBody = @"Hey Alice,

What are you up to this weekend? Monica is throwing one of her parties on
Saturday and I was hoping you could make it.

Will you be my +1?

-- Joey
";

			// In order to reference inline image from the html text, we'll need to add it
			// to builder.LinkedResources and then use its Content-Id value in the img src.
			var image = builder.LinkedResources.Add(inlineImagePath);
			image.ContentId = MimeUtils.GenerateMessageId();

			// Set the html version of the message text
			builder.HtmlBody = string.Format(@"<p>Hey Alice,<br>
<p>What are you up to this weekend? Monica is throwing one of her parties on
Saturday and I was hoping you could make it.<br>
<p>Will you be my +1?<br>
<p>-- Joey<br>
<center><img src=""cid:{0}""></center>", image.ContentId);		

			// Now we just need to set the message body and we're done
			message.Body = builder.ToMessageBody();
			//End MimeKit Sample
			var stream = new MemoryStream();
			message.WriteTo(stream);
			
			stream.Position = 0;
			StringContent MessagePost = new StringContent(Convert.ToBase64String(stream.ToArray()),Encoding.UTF8, "text/plain");

			GraphServiceClient graphServiceClient = new GraphServiceClient(new AuthHelp(redirectUri, scope, mailboxName, clientId));
			var Message = new Message { };
			var sendMailRequest = graphServiceClient.Me.SendMail(Message, null).Request().GetHttpRequestMessage();
			sendMailRequest.Content = MessagePost;
			sendMailRequest.Method = HttpMethod.Post;
			var sendResult = graphServiceClient.HttpProvider.SendAsync(sendMailRequest).Result;
			Console.WriteLine(sendResult.StatusCode);
		}
	}
	class AuthHelp : IAuthenticationProvider
	{
		internal Microsoft.Identity.Client.PublicClientApplication PublicClientApplication { get; set; }
		private string Scope { get; set; }
		public AuthHelp(String redirectUri,string scope,string mailboxName,string clientId)
		{
			Scope = scope;
			HttpClient httpclient = new HttpClient();
			var TenantId = ((dynamic)JsonConvert.DeserializeObject(httpclient.GetAsync("https://login.microsoftonline.com/" + mailboxName.Split('@')[1] + "/v2.0/.well-known/openid-configuration")
			 .Result.Content.ReadAsStringAsync().Result))
			 .authorization_endpoint.ToString().Split('/')[3];

			PublicClientApplicationBuilder pcaConfig = PublicClientApplicationBuilder.Create(clientId)
			 .WithTenantId(TenantId);

			pcaConfig.WithRedirectUri(redirectUri);
			PublicClientApplication = (Microsoft.Identity.Client.PublicClientApplication)pcaConfig.Build();
			var tokenResult = PublicClientApplication.AcquireTokenInteractive(new[] { scope })
			 .WithPrompt(Microsoft.Identity.Client.Prompt.SelectAccount)
			 .WithLoginHint(mailboxName).ExecuteAsync().Result;
		}
		public Task AuthenticateRequestAsync(HttpRequestMessage request)
		{
			var accounts = PublicClientApplication.GetAccountsAsync().Result;
			IAccount account = accounts.FirstOrDefault();
			AuthenticationResult authResult = PublicClientApplication.AcquireTokenSilent(new[] { Scope }, account).ExecuteAsync().Result;
			request.Headers.Authorization = new AuthenticationHeaderValue("bearer", authResult.AccessToken);
			return System.Threading.Tasks.Task.CompletedTask;
		}
	}
}