Outlook 2010 用代码在Outlook explorer中选中一个邮件

这个代码只能在Outlook 2010中使用

using System;using System.Collections.Generic;using System.Linq;using System.Text;using Microsoft.Office.Tools.Ribbon;using Outlook = Microsoft.Office.Interop.Outlook;using System.Windows.Forms;namespace OutlookAddIn18{    public partial class Ribbon1    {        private void Ribbon1_Load(object sender, RibbonUIEventArgs e)        {        }        private void button1_Click(object sender, RibbonControlEventArgs e)        {            Outlook.Application app = Globals.ThisAddIn.Application;            Outlook.Explorer exp = app.ActiveExplorer();            Outlook.MailItem item = app.Session.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox).Items[3];            exp.ClearSelection();            exp.AddToSelection(item);        }    }}