Comment 2 for bug 1860315

What I imagine is that the bug submitter did want to configure a public MTA, so he chose the "Internet site" debconf answer (the "right" answer for his use case), and not "Local only". This led to a nonfunctional setup, e.g. because he has ldap users, and the debconf setup of Postfix supports only very basic configurations.

I too find this less than optimal, however I'm not sure I have a better solution that works better in every case. One idea could be the following: add a debconf question asking on which interface Postfix should listen on. Currently when selecting "Internet site" we get this setting in main.cf:

  inet_interfaces = all

Other valid settings are "loopback-only" or explicit IP addresses [0]. A debconf question, defaulting to "all", could ask on which interfaces/IPs listen on, suggesting to use an internal IP address for testing before exposing the service to the public Internet.

[0] http://www.postfix.org/postconf.5.html#inet_interfaces