[root@relay01 ~]# ls -alZ /usr/sbin/postmap 
-rwxr-xr-x  root root system_u:object_r:postfix_map_exec_t /usr/sbin/postmap
[root@relay01 ~]# getenforce
Enforcing
[root@relay01 ~]# postmap -q 127.0.0.1 cidr:/etc/postfix/access.mx.cidr 
[root@relay01 ~]# setenforce 0
[root@relay01 ~]# postmap -q 127.0.0.1 cidr:/etc/postfix/access.mx.cidr 
REJECT Invalid MX for receipient domain. (127.0.0.0/8 localnet)
[root@relay01 ~]# dmesg | tail -n 2
audit(1192209107.803:48): enforcing=1 old_enforcing=0 auid=4294967295
audit(1192209169.022:49): enforcing=0 old_enforcing=1 auid=4294967295
[root@relay01 ~]#