Comment 7 for bug 1906970

This also breaks installing postfix in autokgtest and holds back fixing sbuild's autopkgtest at the moment.

...
/etc/aliases does not exist, creating it.
WARNING: /etc/aliases exists, but does not have a root alias.

Postfix (main.cf) 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 'systemctl reload postfix'.

Running newaliases
newaliases: warning: valid_hostname: misplaced delimiter: autopkgtest..
newaliases: fatal: file /etc/postfix/main.cf: parameter myhostname: bad parameter value: autopkgtest..
dpkg: error processing package postfix (--configure):
 installed postfix package post-installation script subprocess returned error exit status 75
Setting up libslirp0:amd64 (4.4.0-1) ...
Setting up ipxe-qemu (1.0.0+git-20190125.36a4c85-5ubuntu3) ...
Setting up libasound2:amd64 (1.2.4-1.1build1) ...
Setting up librole-tiny-perl (2.002004-1) ...
Setting up libndctl6:amd64 (71.1-1) ...
dpkg: dependency problems prevent configuration of buildd:
 buildd depends on default-mta | mail-transport-agent; however:
  Package default-mta is not installed.
  Package postfix which provides default-mta is not configured yet.
  Package mail-transport-agent is not installed.
  Package postfix which provides mail-transport-agent is not configured yet.

dpkg: error processing package buildd (--configure):
 dependency problems - leaving unconfigured
Setting up ipxe-qemu-256k-compat-efi-roms (1.0.0+git-20150424.a25a16d-0ubuntu4) ...
...