The postfix package is setting the permissions on the /var/spool/mail directory incorrectly.
$ configure --enable-board=intel-x86-64 --enable-rootfs=glibc_std --enable-kernel=preempt_rt --with-rcpl-version=0017 $ make fs Boot target and log in. Check permissions: root@qemu0:~# ls -l /var/spool/ total 20 drwxr-xr-x 4 root root 4096 Sep 9 11:24 at drwxrwx--- 2 root crontab 4096 Sep 8 08:47 cron drwxr-sr-x 2 postfix nogroup 4096 Sep 8 08:46 mail drwxr-xr-x 16 root postfix 4096 Sep 9 11:24 postfix drwxr-xr-x 2 vmail vmail 4096 Sep 8 08:46 vmail Check which package creates the mail directory: root@qemu0:~# rpm -qf /var/spool/mail shadow-4.1.4.3-r17.0.x86_64 postfix-2.9.5-r17.0.0.x86_64 Check which one sets the permissions incorrectly: root@qemu0:~# rpm -qlv shadow | grep /var/spool/mail drwxr-xr-x 2 root root 0 Sep 8 08:14 /var/spool/mail root@qemu0:~# rpm -qlv postfix | grep /var/spool/mail drwxr-sr-x 2 postfix nogroup 0 Sep 8 08:46 /var/spool/mail Looks like postfix is the culprit.