Instead of that, use the F4 key to launch the search/replace dialog.
This will let you search through everything that has been indexed on your drive, including email.
Keyboard Ninja: Using the Instant Search Shortcut Keys in Microsoft Outlook 2007
If you are using Microsoft Outlook as your email client, you've likely already used the instant search box... but using it can be even more "instant" if you learn how to use a couple of shortcut keys, instead of having to resort to the mouse every time.
