Access outlook unread emails for another user

private void btnCheck_Click(object sender, EventArgs e)
       {
           try
           {
               Microsoft.Office.Interop.Outlook.Application myApp = new Microsoft.Office.Interop.Outlook.Application();
               Microsoft.Office.Interop.Outlook.NameSpace mapiNameSpace = myApp.GetNamespace("MAPI");

               mapiNameSpace.Logon("user2", "pass2", false, false);

               Microsoft.Office.Interop.Outlook.MAPIFolder myInbox = mapiNameSpace.GetDefaultFolder(Microsoft.Office.Interop.Outlook.OlDefaultFolders.olFolderInbox);
               int a = myInbox.UnReadItemCount;
               txtInbox.Text = Convert.ToString(a);

           }
           catch (Exception err)
           {
               MessageBox.Show(err.ToString());
               throw;
           }


       }