messages should sort by, read, and, unread, and by the date in each respective area, then once a message is read it goes into the read messages area and sorts by the date received. in the "unread" area and the "read" area, both of those areas would sort by date. the unread messages would always stay at the top and would be sorted by date. the read messages would be underneath the unread messages and that would also sort by date.