Akin to newsgroup or discussion forum threading, Outlook 2003 lets you sort mail “By Conversation.” This grouping lets you organize mail by topic instead of by date, subject, or sender, and stands as one of the most useful changes in the new version of Outlook. To give this layout a try, click the light gray bar beneath the Inbox header that reads Arranged By: Date. Select Conversation from the drop-down list. Note that after a few hours, messages will “roll up” so that only the most recent is visible. Click the drop-down arrow to show all messages in the conversation thread.