in the file INSTALL.alias in qmail-1.03.tar.gz it says:
* root. Under qmail, root never receives mail. Your system may generate
mail messages to root every night; if you don't have an alias for root,
those messages will bounce. (They'll end up double-bouncing to the
postmaster.) Set up an alias for root in ~alias/.qmail-root. .qmail
files are similar to .forward files, but beware that they are strictly
line-oriented---see dot-qmail.0 for details.
(and in the file INSTALL it says: read INSTALL.alias *evil grin*)
cheers
wolfgang