Mail in Mountain Lion has a VIPs mailbox, which, by default, shows all e-mails from people you have set as VIPs. (To do this, click on an e-mail address and choose Add to VIPs.) But this mailbox, by default, shows all messages received from those addresses, whether they are in an inbox, or whether they are in a folder or in the Archive mailbox.
You can change this, but the setting is in a non-intuitive location. Click on the VIPs mailbox to select it, then choose View > Sort By > Inbox Only.
I would actually like the VIPs mailbox to also show sent messages, which it doesn't; not all the time, but sometimes I'm looking for a sent message to someone in my VIPs list, and it would be easier to be able to find them there than rooting through my Sent mailbox.
Thanks to Dan Frakes for sharing this, and to David Sparks who posted the solution on his website MacSparky.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20121107002309117