It took me a while, but ever since I've gotten my head around Smart Folders (and Smart Playlists and Smart Groups, etc.), I've started to think about the way I use my Mac a bit differently.

Clearly iTunes is the winner in this regard (watch for an upcoming multi-part series about Smart Playlists on The Merlin Show), but the Finder, and Address Book, and Mail.app also have an amazing amount of power rumbling under the hood. So, in the interest of spreading the love, here's four Mail.app Smart Mailboxes that have been rocking my world over the last months.

Inbox, Flagged

This super-basic mailbox is great for whenever you're processing your Inbox(es). You can blow through all the incoming messages, quickly flag anything that needs a response (CMD-SHIFT-L), then view this Smart Mailbox to visually separate the wheat from the chaff. Select all, move them to your "To Respond" folder, and off you go.

Recently Viewed

How many times do you think, "Oh, crap. Where's that message I was looking at last night?" and then you have to either manually drill down through mailboxes or do a (notoriously slow) Mail.app search. This little guy can quickly bubble all the emails you've looked at in the last day or two. I use it all the time.

[ via Red Sweater Blog - Mail Smart Folders ]

Recently Sent

Like the previous Smart Mailbox, this simpleton makes it easy to bubble-up messages that you often need to refer to, but that can be a pain to locate the old-fashioned way. Just shows you any messages you've sent to other people in the last couple days. Yeah, it's obvious, but, man, will you ever love this once you remember it's there.

[ also via Red Sweater Blog - Mail Smart Folders ]

From a given Address Book group

In Address Book:

In Mail.app:

A lot of folks don't realize that Smart Groups even exist in Address Book. Consequently, even fewer know that the contents of both ad hoc and Smart Groups can be searched on from inside Mail.app.

So in this example, I've created a Smart Group with everyone in my Address Book who lives in San Francisco, then I tell Mail.app to group all those peoples' emails in one place.

This is also swell for seeing messages from a company you work with a lot, and it's fantastic for grouping all the email from people in your family.

These particular kind of mailboxes can often be enhanced by ticking off the "Include messages from Sent" box -- that way you also see your own emails to people in this group, allowing you to view your conversations in threads. (Note that this is a lot less useful if your own Address Book entry matches the saved criteria :-) )

If you find yourself searching or -- God forbid -- manually hunting for certain kinds of messages again and again, try to think of a way that Mail.app Smart Mailboxes can do the heavy lifting for you. And, if you add to the mix something like Mail Tags (which adds several very useful search abilities), you can have a lot of automated sexy happening in your email.

Edit: 2007-04-23 11:56:23: Nomenclature corrected -- As Jean points out in comments, these are properly called "Smart Mailboxes" not "Smart Folders." Thanks, Jean!