As with stopping our service, starting it again is trivial:
$ sudo systemctl start postfix $
Note again the confusing silence.
Silence upon command completion isn't unique to systemd, and it's actually something of a philosophy in the Unix and Unix-like world. If a command has done what it's supposed to, the user doesn't need to be told.
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month, and much more.