Have you performed a simple find in MS Outlook 2003 client? The search happens in the folder from older date to the recent one. Doesn't it sound strange?
Ideally I would be more interested in recent mail threads than the older one, since the recent ones will make more relevance. When the search results are shown, the older ones are displayed first and then the recent ones. So one has to wait till the search completes fully, before getting to see the most recent thread.
Are there any tweaks that can be done to Outlook to search in the reverse way? Anyhow the default configuration is really annoying.