foreach (var r in result)
            {
                var newdoc = new UserMailingList
                {
                    UserId = new Guid(r.rcid),
                    MailingListId = listid,
                    StatusId = 0,
                    IsDeleted = false,
                    Timestamp = DateTime.UtcNow
                };
                batch.Add(newdoc);
                batchsize++;
                if (batchsize == 99999)
                {
                    collection.insertmany(batch)
                    batchsize = 0;
                    batch.Clear();
                }
            }