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