By default, /etc/postfix/master.cf should contain the following, which configures Postfix to listen on SMTP port 25.

# ==========================================================================
# service type  private unpriv  chroot  wakeup  maxproc command + args
#               (yes)   (yes)   (yes)   (never) (100)
# ==========================================================================
smtp        inet  n       -       n       -       -       smtpd

If you would like Postfix to listen for requests on SMTPS port 465 or 587, uncomment the submission directive in /etc/postfix/master.cf.

There are additional things you would need to do to configure Postfix for SMTPS port 465 or 587. Check out my article Encrypt SMTP traffic using a public/private key pair (SMTPS port 587).

# ==========================================================================
# service type  private unpriv  chroot  wakeup  maxproc command + args
#               (yes)   (yes)   (yes)   (never) (100)
# ==========================================================================
smtp        inet  n       -       n       -       -       smtpd
submission  inet  n       -       n       -       -       smtpd