All I did was entering
dselect, selected "postfix"
to be installed and accepted the dependencies.
dselect's [I]nstall installs everything.
(You could also run "apt-get install postfix", of course ...)
During the installation you're asked whether your site is an
"Internet site", "Internet site using smarthost", etc. I chose
"Internet site" (as my system shall send and receive mails using
one dedicated host-name "yellow.subnet.at").
The other questions during the installation are:
With this Debian default installation, Postfix works perfectly locally. The following is possible:
Using this Postfix installation to send mails from a different machine
to miscellaneous mailing-addresses (not "yellow-local") is
not possible due to "Relay denied". (See e.g. the config file's
option on this one. My sample main.cf can be found below.)
It's always a good idea to deactivate the VRFY command (which is often used by spammers to easily find out about in/valid mailboxes):
Add to /etc/postfix/main.cf: disable_vrfy_command = yes
I finally got this combination work correctly... Please see my Mailman Howto.
Here's my main.cf including the corresponding Mailman configuration.