Default config files don't match postfix 3

[Christian Ehrhardt ]

With the recent merge to postfix 3 there were quite some changes to its configuration.
Now postfix has a lot to handle those changes in a compatible way so that old configurations should transfer to postfix 3 as good as possible.

In case any incompatibilities occur it reports that in the log and refers to http://www.postfix.org/COMPATIBILITY_README.html to handle them.

While all that is great for anyone migrating from an old system with any kind of custom config, there is not much sense in throwing all these messages out at someone that just freshly installed it.

To Reproduce just:
apt-get remove --purge postfix
apt-get install postfix

in /var/log/mail.log:
Feb 24 11:08:35 lap postfix[25109]: Postfix is running with backwards-compatible default settings
Feb 24 11:08:35 lap postfix[25109]: See http://www.postfix.org/COMPATIBILITY_README.html for details
Feb 24 11:08:35 lap postfix[25109]: To disable backwards compatibility use "postconf compatibility_level=2" and "postfix reload"
Feb 24 11:08:35 lap postfix/master[24994]: reload -- version 3.0.4, configuration /etc/postfix
Feb 24 11:08:35 lap postfix/master[24994]: /etc/postfix/master.cf: line 12: using backwards-compatible default setting chroot=y
[...] there are more like those

So overall I'd suggest we deliver default configuration files that match a valid (not only due to backward compatibility) postfix 3 configuration.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.