package qmail (not installed) failed to install/upgrade: installed qmail package post-installation script subprocess returned error exit status 1

[ehsan milani]

hello
i have a problem with mail
i can not send email over the internet
for example if i want send an email to <email address hidden>
it does not work at all
but it work in my local machine
thanks

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: qmail (not installed)
ProcVersionSignature: Ubuntu 4.15.0-43.46-generic 4.15.18
Uname: Linux 4.15.0-43-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
Date: Mon Jan 28 17:01:03 2019
ErrorMessage: installed qmail package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2019-01-25 (3 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
Python3Details: /usr/bin/python3.6, Python 3.6.7, python3-minimal, 3.6.7-1~18.04
PythonDetails: N/A
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2.1
 apt 1.6.6ubuntu0.1
SourcePackage: netqmail
Title: package qmail (not installed) failed to install/upgrade: installed qmail package post-installation script subprocess returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)