Hello Oliver, You must run next command:
# systemctl status postfix* ● postfix@-.service - Postfix Mail Transport Agent (instance -) Loaded: loaded (/lib/systemd/system/postfix@.service; disabled; vendor preset: enabled) Active: active (running) since Fri 2018-02-23 09:39:28 CET; 30min ago Docs: man:postfix(1) Process: 2970 ExecStart=/usr/sbin/postmulti -i - -p start (code=exited, status=0/SUCCESS) Process: 2569 ExecStartPre=/usr/lib/postfix/configure-instance.sh - (code=exited, status=0/SUCCESS) Tasks: 3 (limit: 4915) CGroup: /system.slice/system-postfix.slice/postfix@-.service ├─3249 /usr/lib/postfix/sbin/master -w ├─3251 pickup -l -t unix -u -c └─3252 qmgr -l -t unix -u ● postfix.service - Postfix Mail Transport Agent Loaded: loaded (/lib/systemd/system/postfix.service; enabled; vendor preset: enabled) Active: active (exited) since Fri 2018-02-23 09:39:28 CET; 30min ago Process: 3253 ExecStart=/bin/true (code=exited, status=0/SUCCESS) Main PID: 3253 (code=exited, status=0/SUCCESS) Tasks: 0 (limit: 4915) CGroup: /system.slice/postfix.service Best Regards Jan -- http://www.fuky.org