If you’re using any sort of email client, then you’ve probably stored up hundreds or even thousands of deleted messages that you thought were gone forever.
You should delete them. Not only to get rid of information that you don’t want falling into the wrong hands, but also because you need to save space.
There’s a quick way to do this in Outlook. You could always right-click the deleted items folder and then hit “delete”, but you can also head to the File menu, press Info, and then hit “cleanup tools”. There, you’ll be able to delete the Deleted Items folder straight from there.