I discovered by accident that you can file a message in Mail without first manually opening the drawer to view the folders.
Try this: drag a message header from the inbox toward the edge of the Mail window. Watch the drawer automatically pop open! Continue dragging the message to the desired folder (or spring-loaded subfolder), release the message, move the mouse back into the inbox window, and presto, the drawer will automatically close!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20021211060556205