Entourage doesn't support true threading by reference like Mail; as a
result, it doesn't offer multiple levels of indentation to visually indicate
which messages in a thread are in reply to which.
Some users choose to use Grouping (View > Arrange By) instead, though it's
not as powerful. I use a custom arrangement like this (View > Arrange By >
Edit Custom Arrangements):
Group items by: Subject
Sort groups by: Sent Newest on Top
Sort items within groups by: Sent Oldest on Top
Default display for groups: Expanded
You can try editing & applying that arrangement to folders to see how you
like it.
