public sealed class MyOutlook
    {
        // http://csharpindepth.com/Articles/General/Singleton.aspx - version 2
        #region Singleton

        private static NovaOutlook instance;
        private static readonly object padlock = new object();

        private Calendar calendar;

        private MyOutlook()
        {
            OutlookApp = new OutlookApplication();
        }

        public static MyOutlook Instance
        {
            get
            {
                lock (padlock)
                {
                    return instance ?? (instance = new MyOutlook());
                }
            }
        }

        #endregion

        #region Properties

        public Calendar Calendar
        {
            get
            {
                lock (padlock)
                {
                    return calendar ?? (calendar = new Calendar(OutlookApp));
                }
            }
        }

        private OutlookApplication OutlookApp { get; set; }

        #endregion
    }