Im at work, just playing online trying to get smartfolders on .mac at least, i have read you can create them on .mac, but all i can do is just create a folder, not create the rule, the info below is taken from .mac help but doesnt really help
To organize messages in folders:
To see the messages in a folder, choose the folder from the Go To Folder pop-up menu.
To move a message you are reading into another folder, choose the folder from the Move To Folder pop-up menu.
To move a message without opening it, or to move several messages at once, click the checkboxes next to them in the message list before you choose the folder.
To add, delete, rename, or empty a folder, or to see a list of your folders and their total size, choose Show All Folders from the Go To Folder pop-up menu.