public override object GetDataSource()
        {
            List <String> data = new List <String>();

            LightboxSentFinder finder = new LightboxSentFinder();

            finder.SenderId = SessionInfo.Current.User.UserId.GetValueOrDefault();
            EntityList <LightboxSent> sentLightboxes = LightboxSent.FindMany(finder);

            foreach (LightboxSent lbs in sentLightboxes)
            {
                if (!data.Contains(lbs.RecipientEmail.ToLower()))
                {
                    data.Add(lbs.RecipientEmail.ToLower());
                }
            }

            return(data);
        }