It's happened to all of us. You delete an email on purpose or by accident and then discover later that you need to refer to the information.
Deleting and Recovering Items in Outlook
There are two ways to delete items in Outlook. The most common is to highlight a message or calendar item and click 'Delete' (either the icon in the toolbar, the menu item under 'Edit' or by right-clicking and selecting 'Delete' from the popup menu). Items deleted this way can be recovered from your Deleted Items Folder, if you haven't emptied the folder.
You can also delete items by pressing Shift-Delete which permanently deletes the item without first placing it in the Deleted Items Folder.
If you've already emptied your Deleted Items Folder or permanently deleted an item with Shift-Delete, you can still recover an item within three weeks of deleting it.
To Recover Deleted Items: