In Outlook 2007, the handy right-click “Search in this folder” option has disappeared. In replace, we now have the Search box on the right top. By default, the search will only search in the current folder. Subfolders are not included in the search results!
I’ve been looking for a GPO to make “Search in subfolders” the default, but it looks like this is not possible at all. As a workaround, I’ve decided to instruct the users in my company to click the arrow, and then select “Search All mail items”:
When selecting the “Search all mail items” option, you will be directed to another mail folder. In the “Mail Folders” pane on the left, “All Mail Items” should be selected now.