Как показать непрочитанную электронную почту жирным шрифтом при разборе электронной почты с помощью IMAP в C#

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Привет,
Я занимаюсь разбором электронной почты на C# с использованием протокола IMAP
Любой метод или другой способ показать непрочитанное письмо или сообщение в жирном формате

заранее спасибо

Что я уже пробовал:

private void ReceiveMails()
		{
			// Disable buttons while working
			connectAndRetrieveButton.Enabled = false;
			uidlButton.Enabled = false;
			progressBar.Value = 0;

			try
			{
				if (pop3Client.Connected)
					pop3Client.Disconnect();
				pop3Client.Connect(popServerTextBox.Text, int.Parse(portTextBox.Text), useSslCheckBox.Checked);
				pop3Client.Authenticate(loginTextBox.Text, passwordTextBox.Text);
				int count = pop3Client.GetMessageCount();
				totalMessagesTextBox.Text = count.ToString();
				messageTextBox.Text = "";
				messages.Clear();
				listMessages.Nodes.Clear();
				listAttachments.Nodes.Clear();

				int success = 0;
				int fail = 0;
				for (int i = count; i >= 1; i -= 1)
				{
					// Check if the form is closed while we are working. If so, abort
					if (IsDisposed)
						return;

					// Refresh the form while fetching emails
					// This will fix the "Application is not responding" problem
					Application.DoEvents();

					try
					{
						Message message = pop3Client.GetMessage(i);

						// Add the message to the dictionary from the messageNumber to the Message
						messages.Add(i, message);

						// Create a TreeNode tree that mimics the Message hierarchy
						TreeNode node = new TreeNodeBuilder().VisitMessage(message);

						// Set the Tag property to the messageNumber
						// We can use this to find the Message again later
						node.Tag = i;

						// Show the built node in our list of messages
						listMessages.Nodes.Add(node);

						success++;
					} catch (Exception e)
					{
						DefaultLogger.Log.LogError(
							"TestForm: Message fetching failed: " + e.Message + "\r\n"+
							"Stack trace:\r\n" +
							e.StackTrace);
						fail++;
					}

					progressBar.Value = (int)(((double)(count-i)/count) * 100);
				}

				MessageBox.Show(this, "Mail received!\nSuccesses: " + success + "\nFailed: " + fail, "Message fetching done");

				if(fail > 0)
				{
					MessageBox.Show(this,
					                "Since some of the emails were not parsed correctly (exceptions were thrown)\r\n" +
					                "please consider sending your log file to the developer for fixing.\r\n" +
					                "If you are able to include any extra information, please do so.",
					                "Help improve OpenPop!");
				}
			} catch (InvalidLoginException)
			{
				MessageBox.Show(this, "The server did not accept the user credentials!", "POP3 Server Authentication");
			} catch (PopServerNotFoundException)
			{
				MessageBox.Show(this, "The server could not be found", "POP3 Retrieval");
			} catch(PopServerLockedException)
			{
				MessageBox.Show(this, "The mailbox is locked. It might be in use or under maintenance. Are you connected elsewhere?", "POP3 Account Locked");
			} catch (LoginDelayException)
			{
				MessageBox.Show(this, "Login not allowed. Server enforces delay between logins. Have you connected recently?", "POP3 Account Login Delay");
			} catch (Exception e)
			{
				MessageBox.Show(this, "Error occurred retrieving mail. " + e.Message, "POP3 Retrieval");
			} finally
			{
				// Enable the buttons again
				connectAndRetrieveButton.Enabled = true;
				uidlButton.Enabled = true;
				progressBar.Value = 100;
			}
		}

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