Chances are, Outlook Express is not mad at you or trying to preserve any single email you get. Most probably, the Deleted Items folder has been damaged — and it can be repaired.
Fix Outlook Express When Deleting Messages Does Not Work
To make Outlook Express delete messages again:
- Go to the Deleted Items folder in Outlook Express.
- Move all messages you may want to keep to your Inbox or another folder.
- Shut down Outlook Express.
- Open your Outlook Express store folder.
- Delete the "Deleted Items.dbx" file.
- Restart Outlook Express.
- Make sure you empty the Deleted Items folder frequently (say, once a week).