Mail.app Rules

I've just started using this feature and can't help but want more functionality. It would be great if you could use more complex date equations like: "If" received on "Saturday" + "Sunday" = Auto-reply "xxx"



Also noticed a bug where if you've assigned an "auto-reply" to an incoming message when you click the "arrow" to see the linked reply email an error message shows up saying it can't find the message. Not very Apple-like \