Outlook's performance - in fact, whether or not it works at all - is directly impacted by the number and size of the messages and entries in the program. As you approach about 10,000 messages in total across all your folders (not including the archives), Outlook begins to act badly and could, in some cases, stop accepting new emails. And if you have large attachments with your messages, it's even more serious!
By default, Outlook keeps everything in one outlook.pst file: messages, calendar entries, contacts, etc. When that file gets too big, Outlook will warn you and ask you to clean up your mailbox (I'll do a post on the cleanup process...a task for another day!). This entry is all about a simple keystroke that permanently deletes your selected item(s).
When you delete things from the deleted folder, they are permanently deleted. They are not in the recycle bin; they are gone. You can bypass the Deleted folder and delete things directly by holding the Shift key when you delete. Whether you use the delete key on your keyboard or the delete icon on the toolbar, holding the Shift key down when you execute the command permanently deletes the entry. Outlook warns you with this message:

If you click 'yes', the entry does not go in your deleted folder and it's *poof* gone.
When you select multiple messages and use shift-delete, they are all permanently deleted. I use this a lot for my incoming junk mail.
So from now on, when you delete stuff you don't need, use shift-delete to get rid of em permanently.
