Mail Messages Don't Show Addressees

I'm running Mountain Lion 10.8.2. Since I installed it, my saved email messages no longer show the BCC addressees. Is there a way I can make them display them? It makes it really difficult to send future emails to the same receipients if I don't remember who they are. I always put the "Sent" message into a separate file folder called "Mail." Should I do something different? Thank you in advance for your help.