Actually, I meant it without qualifiers.  We have 2^9 possible permissions.  One
of them is to allow anyone (that can attach the fs) to do anything.  I can see
when that's a useful thing.  For the /mail/box directory its a bit too much.
Geoff Collyer suggested making the 'a' bit on directories mean that you can't
rename files (ala unix sticky bit?).  I wouldn't mind that for the mail directory.