See "systemctl status postfix.service" and "journalctl -xe" for details.

[root@hadoop002 tmp]# systemctl enable postfix && systemctl start postfix

Job for postfix.service failed because the control process exited with error code. See "systemctl status postfix.service" and "journalctl -xe" for details.
[root@hadoop002 tmp]# systemctl status postfix.service
● postfix.service - Postfix Mail Transport Agent
   Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Wed 2020-01-22 20:05:57 CST; 14s ago
  Process: 1227 ExecStart=/usr/sbin/postfix start (code=exited, status=1/FAILURE)
  Process: 1224 ExecStartPre=/usr/libexec/postfix/chroot-update (code=exited, status=0/SUCCESS)
  Process: 1221 ExecStartPre=/usr/libexec/postfix/aliasesdb (code=exited, status=75)

Jan 22 20:05:55 hadoop002 systemd[1]: Starting Postfix Mail Transport Agent...
Jan 22 20:05:55 hadoop002 aliasesdb[1221]: /usr/sbin/postconf: fatal: parameter inet_interfaces: no local interface found for ::1
Jan 22 20:05:56 hadoop002 aliasesdb[1221]: newaliases: fatal: parameter inet_interfaces: no local interface found for ::1
Jan 22 20:05:56 hadoop002 postfix[1227]: fatal: parameter inet_interfaces: no local interface found for ::1
Jan 22 20:05:57 hadoop002 systemd[1]: postfix.service: control process exited, code=exited status=1
Jan 22 20:05:57 hadoop002 systemd[1]: Failed to start Postfix Mail Transport Agent.
Jan 22 20:05:57 hadoop002 systemd[1]: Unit postfix.service entered failed state.
Jan 22 20:05:57 hadoop002 systemd[1]: postfix.service failed.

[root@hadoop002 ~]# vim /etc/postfix/main.cf

#inet_interfaces = all
#inet_interfaces = $myhostname
#inet_interfaces = $myhostname, localhost
inet_interfaces = all

# Enable IPv4, and IPv6 if supported
inet_protocols = ipv4