SOLVED:
It looked like a permission problem:
[root@office log]# journalctl -xe
-- Unit amavisd.service has begun starting up.
Jan 23 23:37:49 office.yna11.com amavisd[11715]: Config file "/etc/amavisd/amavisd.conf" should not be owned by EUID 990, at /usr/sbin/amavisd line 2150.
Jan 23 23:37:49 office.yna11.com systemd[1]: amavisd.service: control process exited, code=exited status=255
Jan 23 23:37:49 office.yna11.com systemd[1]: Failed to start Amavisd-new is an interface between MTA and content checkers..
-- Subject: Unit amavisd.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/li … temd-devel
--
-- Unit amavisd.service has failed.
--
-- The result is failed.
___________________________
ls -l /etc/amavisd/
-rw-r----- 1 amavis amavis 28238 Jan 23 23:09 amavisd.conf
-rw-r--r-- 1 root root 36776 Nov 29 19:32 amavisd.conf.2016.11.29.19.28.49
-rw-r----- 1 root root 28238 Jan 2 20:59 amavisd.conf.bck
-rw-r----- 1 root amavis 28412 Jan 9 21:16 amavisd.conf.bck2
___________________
SOLUTION:
chown root:root amavisd.conf
chmod 0644 amavisd.conf
ls -l -->
-rw-r--r-- 1 root root 28238 Jan 23 23:09 amavisd.conf
-rw-r--r-- 1 root root 36776 Nov 29 19:32 amavisd.conf.2016.11.29.19.28.49
-rw-r----- 1 root root 28238 Jan 2 20:59 amavisd.conf.bck
-rw-r----- 1 root amavis 28412 Jan 9 21:16 amavisd.conf.bck2
UFFF ;-)