If I understand the problem correctly, this should work. You can see all search filters available here: EWS Search Filters
ItemView view = new ItemView(int.MaxValue);
FindItemsResults<Item> findResults;
view.PropertySet = itempropertyset;
SearchFilter searchFilter =
new SearchFilter.IsGreaterThan(ItemSchema.DateTimeReceived, DateTime.Now.AddDays(-3));
findResults = service.FindItems(WellKnownFolderName.Inbox, searchFilter, view);