Exchange has a feature called 'deleted item recovery', usually referred to as the
dumpster. When it is enabled, when you empty your deleted items folder, items are
placed in the dumpster for a server-configured number of days. The client can choose
to retrieve the items from the dumpster until that number of days is up.
Each folder essentially has its own dumpster, and generally the dumpster for the deleted
items folder is the most commonly used one (since most users tend to delete items
from other folders and then empty the deleted items folder).
It is possible, however, to delete an item and have it remain in that folder's dumpster,
by shift+deleting the item. In that case, the item would remain in the dumpster for
By default, Outlook only allows you to access the "Recover Deleted Items" menu option
if the deleted items folder is selected. By following the steps in KB article #178630,
you can make this menu available in any folder.
Another way of getting access to these items is to use OWA (requires Exchange 2000
SP1 and later). Open the target folder with a URL like this:
From this interface, you can then retrieve the items (they will be moved back to the
folder from which they were deleted) or delete them from the dumpster.
This was the first feature I ever designed when I worked on Outlook Web Access, so
if you hate it, it's completely my fault. :-)