MailKit oAuth Example

			String ClientId = "20773535-6b8f-4f3d-8f0e-4b7710d79afe";
			string UserName = "user@domain.com";
			string scope = "https://outlook.office.com/SMTP.Send";
			string redirectUri = "msal20773535-6b8f-4f3d-8f0e-4b7710d79afe://auth";
			string From = "Fromouser@domain.com;
			String To = "Touser@domain.com";
			String SMTPServer = "smtp.office365.com";
			Int32 SMTPPort = 587;

			PublicClientApplicationBuilder pcaConfig = PublicClientApplicationBuilder.Create(ClientId)
			 .WithAuthority(AadAuthorityAudience.AzureAdMultipleOrgs);

			pcaConfig.WithRedirectUri(redirectUri);
			var TokenResult = await pcaConfig.Build().AcquireTokenInteractive(new[] { scope })
			 .WithPrompt(Prompt.Never)
			 .WithLoginHint(UserName).ExecuteAsync();


			var message = new MimeMessage();
			message.From.Add(MailboxAddress.Parse(From));
			message.To.Add(MailboxAddress.Parse(To));
			message.Subject = "Test";
			message.Body = new TextPart("plain")
			{
				Text = @"Hey Joe"
			};
			using (var client = new SmtpClient())
			{
				client.Connect(SMTPServer, SMTPPort, SecureSocketOptions.StartTls);
				var oauth2 = new SaslMechanismOAuth2(UserName, TokenResult.AccessToken);
				client.Authenticate(oauth2);

				await client.SendAsync(message);
				client.Disconnect(true);
			}