For instance, if you are using Outlook 2007 there’s the Instant search box on every folder. If you click the drop-down and then select Recent Searches, you’ll see a list of your most recent searches…. but there’s no way to clear it!
This is where the brilliant application OutlookTools comes into the picture. It’s a sort of TweakUI for Outlook, and allows you to configure a ton of settings very easily, including the ability to let you clear the MRU lists.
You’ll notice that there are a lot of options you can choose from. Make sure you have the correct profile selected in the drop-down list, and then click the buttons to clear. Odd that there’s no Clear All button, isn’t it?
You can also clear the auto-complete email address cache using a different method.
Download OutlookTools from HowTo-Outlook