The addition of color categories in Outlook 2007 makes it very easy to identify specific messages or types of messages. For example, you might categorize messages you receive from specific people so that you can see at a glance that a message is from a particular person.

In some situations, you might want to customize a view so that you see only messages that have certain categories. For example, assume that you have categorized messages for two projects, each with a unique category. Now you want to view all messages from both projects. The easiest way to do that is to filter the view so that it shows only messages with those two categories assigned to them. You can do that using a custom view or a search folder.