package postfix 2.11.3-1ubuntu2 failed to install/upgrade: subprocess new pre-installation script returned error exit status 1

[Vertago1]

postfix wasn't being used on the machine but was installed for a dependency

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: postfix 2.11.3-1ubuntu2
ProcVersionSignature: Ubuntu 4.2.0-30.36-generic 4.2.8-ckt3
Uname: Linux 4.2.0-30-generic x86_64
NonfreeKernelModules: vboxpci vboxnetadp vboxnetflt vboxdrv fglrx
ApportVersion: 2.20-0ubuntu3
Architecture: amd64
Date: Sun Mar 13 14:14:04 2016
DuplicateSignature: InvalidHostOrDomain
ErrorMessage: subprocess new pre-installation script returned error exit status 1
EtcMailname: *** /etc/mailname does not exist ***
Hostname: vertago1-FX8350
InstallationDate: Installed on 2014-04-11 (702 days ago)
InstallationMedia: Kubuntu 14.04 LTS "Trusty Tahr" - Beta amd64 (20140326.2)
PostconfMydomain: Error: command ['/usr/sbin/postconf', '-h', 'mydomain'] failed with exit code 1: /usr/sbin/postconf: fatal: open /etc/postfix/main.cf: No such file or directory
PostconfMyhostname: Error: command ['/usr/sbin/postconf', '-h', 'myhostname'] failed with exit code 1: /usr/sbin/postconf: fatal: open /etc/postfix/main.cf: No such file or directory
PostconfMyorigin: Error: command ['/usr/sbin/postconf', '-h', 'myorigin'] failed with exit code 1: /usr/sbin/postconf: fatal: open /etc/postfix/main.cf: No such file or directory
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1
 apt 1.2.4
ResolvConf:
 # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
 # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
 nameserver 127.0.1.1
SourcePackage: postfix
Title: package postfix 2.11.3-1ubuntu2 failed to install/upgrade: subprocess new pre-installation script returned error exit status 1
UpgradeStatus: Upgraded to xenial on 2016-03-13 (0 days ago)

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #1531299, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.