Needed some permission fixes

I think the postfix installer on debian set spermissions after each upgrade. (postfix set-permissions). So changing permission does not have a permanent effect.

If you want to use this plugin after all without changing the owner of /var/spool/postfix subdirectories – then here is what I’ve done:

# add user nagios to postfix group
usermod -a -G postfix nagios

# add user nagios to postdrop group
usermod -a -G postdrop nagios

# add user nagios to root group (very insecure)
usermod -a -G root nagios

# allow directory listing for all postfix directories
find /var/spool/postfix -type d -exec chmod g+x {} +