What about just
# yum install rpm-build openldap-devel cyrus-sasl-devel
# wget
http://repos.oostergo.net/7/SRPMS/postfix-3.2.3-1.el7.centos.src.rpm
# rpmbuild --rebuild postfix-3.2.3-1.el7.centos.src.rpm
# rpm -Uvh /root/rpmbuild/RPMS/x86_64/postfix-3.2.3-1.el7.centos.x86_64.rpm
# touch /etc/postfix/postfix-files
# postfix set-permissions
# systemctl restart postfix
# systemctl status postfix
● postfix.service - Postfix Mail Transport Agent
Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled; vendor preset: disabled)
Active: active (running) since Mon 2017-10-09 12:52:07 NOVT; 6s ago
Process: 20748 ExecStop=/usr/sbin/postfix stop (code=exited, status=0/SUCCESS)
Process: 20766 ExecStart=/usr/sbin/postfix start (code=exited, status=0/SUCCESS)
Process: 20763 ExecStartPre=/usr/libexec/postfix/chroot-update (code=exited, status=0/SUCCESS)
Process: 20759 ExecStartPre=/usr/libexec/postfix/aliasesdb (code=exited, status=0/SUCCESS)
Main PID: 20840 (master)
CGroup: /system.slice/postfix.service
├─20840 /usr/libexec/postfix/master -w
├─20841 pickup -l -t fifo -u
└─20842 qmgr -l -t fifo -u
Oct 09 12:52:07 ppu17-5.demo.pp.plesk.ru postfix[20766]: Postfix is running with backwards-compatible default settings
Oct 09 12:52:07 ppu17-5.demo.pp.plesk.ru postfix[20766]: See
Postfix Backwards-Compatibility Safety Net for details
Oct 09 12:52:07 ppu17-5.demo.pp.plesk.ru postfix[20766]: To disable backwards compatibility use "postconf compatibility_level=2" and "postfix reload"
Oct 09 12:52:07 ppu17-5.demo.pp.plesk.ru postfix/postfix-script[20835]: warning: not set-gid or not owner+group+world executable: /usr/sbin/postdrop
Oct 09 12:52:07 ppu17-5.demo.pp.plesk.ru postfix/postfix-script[20838]: starting the Postfix mail system
Oct 09 12:52:07 ppu17-5.demo.pp.plesk.ru postfix/master[20840]:
daemon started -- version 3.2.3, configuration /etc/postfix