Just How Smart is a Smart Mailbox?
Smart Mailboxes are a sort of combination mailbox and filter, but they don’t store messages like a mailbox and neither do they move your messages like a filter! The job of a Smart Mailbox is to create "virtual" mailboxes on the fly into which messages will appear without actually be moved from wherever you’ve placed them. Suppose that you already have filters that move messages from three of your clients—Bob Jones, Sarah Levy, and Leslie Chan—into mailboxes of their own. But at the same time, you want to keep these messages all together in another folder that you’ve set aside for, say, your clients in the Midwest instead of those on the East Coast.
Smart Mailboxes take care of this problem very easily. Instead of actually moving a message from the regular mailbox into the Smart Mailbox, its built-in rules merely list the message in the Smart Mailbox. The message itself remains wherever you put it. Note that while deleting a Smart Mailbox does nothing to the messages it contained, if you delete individual messages within a Smart Mailbox, that message will be moved into the Trash. This somewhat inconsistent behavior makes Smart Mailboxes useful but potentially dangerous tools, so handle with care.
Figure 8 Smart Mailboxes are a essentially a way to view, manage, or delete messages from multiple mailboxes—all in one window.