[imp] UW security

[test account]

Taken from the 
UW docs/config file

    Example 5: suppose you want to disable non-namespace access to the
filesystem root and other users' names, but do not want to go to the
extreme of chroot() and you want to allow access to a traditional UNIX
format INBOX in the mail spool directory.  You need to change variable
restrictBox, changing the line which reads:

static short restrictBox = NIL;	/* is a restricted box */
 to be:
static short restrictBox = -1;	/* is a restricted box */

Other values to set in restrictBox can be found in env_unix.h.