All e-mail are records in a database (the .pst file). When you "delete"
in Outlook, you do not delete at all. Instead you *move* the item into
the Deleted Items folder. To "permanently" delete (which really is not
deleting yet), you either:
- Delete an item from the Deleted Items folder.
- Or, use Shift+Del on an item in any folder.
What a permanent delete does is tag that item (its record) as "deleted".
Outlook will not display delete-tagged records. Not until you compact
the database which commits a purge operation are delete-tagged records
physically removed from the database. Because the delete-tagged records
get physically removed from the database is why a compact results in
reducing the size of that database.