As I process my email and delete my messages the number of messages on the current page reduce. When the last email is reached and I press down arrow, display takes me to the next page. However, next is now recomputed and the highlighted message is no longer the next message. Messages from the next page have now moved to the first page.
If you could stop the interface from recalculating next page when a down arrow (next) is pressed, actual next message will be highlighted. Perhaps recalculation can be limited to navigation at folder, category, or mailbox level.