Comment 25 for bug 1595096

Found this one hanging in proposed.
Did the verification (using local-only config in postfix) all else can be seen in the log.
The vim in between enabled proposed.

root@xenial-test:~# apt install postfix
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  comerr-dev krb5-multidev libgssrpc4 libkadm5clnt-mit9 libkadm5srv-mit9 libkdb5-8 libpq-dev libsensors4 libssl-dev libssl-doc sysstat
Use 'apt autoremove' to remove them.
Suggested packages:
  procmail postfix-mysql postfix-pgsql postfix-ldap postfix-pcre sasl2-bin dovecot-common postfix-cdb mail-reader postfix-doc
The following NEW packages will be installed:
  postfix
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 1152 kB of archives.
After this operation, 3697 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu xenial/main amd64 postfix amd64 3.1.0-3 [1152 kB]
Fetched 1152 kB in 0s (1311 kB/s)
Preconfiguring packages ...
Selecting previously unselected package postfix.
(Reading database ... 36919 files and directories currently installed.)
Preparing to unpack .../postfix_3.1.0-3_amd64.deb ...
Unpacking postfix (3.1.0-3) ...
Processing triggers for libc-bin (2.23-0ubuntu9) ...
Processing triggers for systemd (229-4ubuntu19) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for ufw (0.35-0ubuntu2) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up postfix (3.1.0-3) ...
Adding group `postfix' (GID 118) ...
Done.
Adding system user `postfix' (UID 113) ...
Adding new user `postfix' (UID 113) with group `postfix' ...
Not creating home directory `/var/spool/postfix'.
Creating /etc/postfix/dynamicmaps.cf
Adding group `postdrop' (GID 119) ...
Done.
setting myhostname: xenial-test.lxd
setting alias maps
setting alias database
changing /etc/mailname to xenial-test.lxd
setting myorigin
setting destinations: $myhostname, xenial-test.lxd, localhost.lxd, localhost
setting relayhost:
setting mynetworks: 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
setting mailbox_size_limit: 0
setting recipient_delimiter: +
setting inet_interfaces: loopback-only
setting default_transport: error
setting relay_transport: error
setting inet_protocols: all
WARNING: /etc/aliases exists, but does not have a root alias.

Postfix is now set up with a default configuration. If you need to make
changes, edit
/etc/postfix/main.cf (and others) as needed. To view Postfix configuration
values, see postconf(1).

After modifying main.cf, be sure to run '/etc/init.d/postfix reload'.

Running newaliases
Processing triggers for libc-bin (2.23-0ubuntu9) ...
Processing triggers for systemd (229-4ubuntu19) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for ufw (0.35-0ubuntu2) ...
root@xenial-test:~#
root@xenial-test:~#
root@xenial-test:~#
root@xenial-test:~#
root@xenial-test:~# postmulti -e init
root@xenial-test:~# postmulti -I postfix-example -G mta -e create
postfix/postmulti-script: fatal: Missing main.cf prototype: /etc/postfix/main.cf.proto
root@xenial-test:~#
root@xenial-test:~#
root@xenial-test:~# vim /etc/apt/sources.list
root@xenial-test:~# apt update
Hit:1 http://archive.ubuntu.com/ubuntu xenial InRelease
Hit:2 http://security.ubuntu.com/ubuntu xenial-security InRelease
Hit:3 http://archive.ubuntu.com/ubuntu xenial-updates InRelease
Hit:4 http://archive.ubuntu.com/ubuntu xenial-backports InRelease
Get:5 http://archive.ubuntu.com/ubuntu xenial-proposed InRelease [253 kB]
Get:6 http://archive.ubuntu.com/ubuntu xenial-proposed/main Sources [83.3 kB]
Get:7 http://archive.ubuntu.com/ubuntu xenial-proposed/universe Sources [38.7 kB]
Get:8 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages [106 kB]
Get:9 http://archive.ubuntu.com/ubuntu xenial-proposed/main Translation-en [40.6 kB]
Get:10 http://archive.ubuntu.com/ubuntu xenial-proposed/universe amd64 Packages [48.4 kB]
Get:11 http://archive.ubuntu.com/ubuntu xenial-proposed/universe Translation-en [24.2 kB]
Fetched 594 kB in 0s (960 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
1 package can be upgraded. Run 'apt list --upgradable' to see it.
root@xenial-test:~# apt install postfix
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  comerr-dev krb5-multidev libgssrpc4 libkadm5clnt-mit9 libkadm5srv-mit9 libkdb5-8 libpq-dev libsensors4 libssl-dev libssl-doc sysstat
Use 'apt autoremove' to remove them.
Suggested packages:
  procmail postfix-mysql postfix-pgsql postfix-ldap postfix-pcre sasl2-bin dovecot-common postfix-cdb mail-reader postfix-doc
The following packages will be upgraded:
  postfix
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 1152 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 postfix amd64 3.1.0-3ubuntu0.1 [1152 kB]
Fetched 1152 kB in 0s (3964 kB/s)
Preconfiguring packages ...
(Reading database ... 37110 files and directories currently installed.)
Preparing to unpack .../postfix_3.1.0-3ubuntu0.1_amd64.deb ...
Unpacking postfix (3.1.0-3ubuntu0.1) over (3.1.0-3) ...
Processing triggers for libc-bin (2.23-0ubuntu9) ...
Processing triggers for ufw (0.35-0ubuntu2) ...
Processing triggers for systemd (229-4ubuntu19) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up postfix (3.1.0-3ubuntu0.1) ...

Postfix configuration was not changed. If you need to make changes, edit
/etc/postfix/main.cf (and others) as needed. To view Postfix configuration
values, see postconf(1).

After modifying main.cf, be sure to run '/etc/init.d/postfix reload'.

Running newaliases
Processing triggers for libc-bin (2.23-0ubuntu9) ...
root@xenial-test:~#
root@xenial-test:~#
root@xenial-test:~#
root@xenial-test:~#
root@xenial-test:~# postmulti -e init
root@xenial-test:~# postmulti -I postfix-example -G mta -e create
root@xenial-test:~# postmulti -l
- - y /etc/postfix
postfix-example mta n /etc/postfix-example