Setting rules for outgoing e-mail

Is there a way to set rules for outgoing e-mail? For example, any mail sent from user1@mydomain.com to an outside user should automatically get copied to user1's boss, user2@mydomain.com. This can get very complicated, depending on what you want to do. There are several products out there that perform this function, especially to comply with NASD rules for supervision. Legato has a product for this that works very well. As for a rule, you could try writing some script, but it could get messy and bog down your router. Server-based rules are really only for incoming messages, not outgoing ones.