package ssmtp 2.64-8ubuntu1 [modified: usr/sbin/ssmtp] failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

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ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: ssmtp 2.64-8ubuntu1 [modified: usr/sbin/ssmtp]
ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
Uname: Linux 4.4.0-22-generic i686
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: i386
Date: Fri Jun 3 11:36:56 2016
DuplicateSignature:
 package:ssmtp:2.64-8ubuntu1 [modified: usr/sbin/ssmtp]
 Setting up ssmtp (2.64-8ubuntu1) ...
 hostname: Name or service not known
 dpkg: error processing package ssmtp (--configure):
  subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2014-12-30 (520 days ago)
InstallationMedia: Lubuntu 13.10 "Saucy Salamander" - Release i386 (20131016.1)
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.12~ubuntu16.04.1
SourcePackage: ssmtp
Title: package ssmtp 2.64-8ubuntu1 [modified: usr/sbin/ssmtp] failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: Upgraded to xenial on 2016-04-22 (41 days ago)