If you're anything like me, you tend to hold on to your email for months, years, or pretty much all of eternity. Now that I have things like Google Apps for Your Domain and IMAP, I can literally keep as much of my email as I want, and always get access to my full message history. On top of this, I have 7 inboxes to check.

There are several advantages to this system as far as I can see - I never have to worry that someone has the wrong email address, or one I no longer use, because I always know the message will arrive on my desktop, but at the same time live somewhere on dark and dank hard drive deep in the Google infrastructure, wherever that may be.

Here is my big problem: I get dozens of messages a day. On the day I wrote this tutorial I had received 20 messages by noon! How on earth am I supposed to keep track of the messages I want to keep, without abandoning my pack rat nature?

My solution for now: Smart Mailboxes. You've at least seen Smart Playlists in iTunes - the program ships with a few of them baked in. The Finder also features a few pre-selected searches under "search for" on Leopard. Apple's Mail.app has had Smart Mailboxes for some time now, and it's about time you got a little more insight into what is going on with your mail.

The very simplest way to create a Smart Mailbox is to use the little search box in the top right of your Mail window and push the Save button. That's really all there is to it. You can choose a few simple options from the popup box - the application has already chosen a sensible folder name for you, based on what you searched. You could try searching for something related to a big project you're working on, or all the messages from a particular friend, or a group of friends. The possibilities are endless.

What are some of your favorite Smart Mailbox formulas? I'd love to see them in a comment.