==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 0.9.8
- Linux/BSD distribution name and version: Ubuntu 18.04.1 LTS
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? N
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I think this may be an issue with the Latest Stable release of iRedMail being intended for Ubuntu 18.04 LTS? Ubuntu 18.0.4.1 LTS has been standard since July 2018 and contains security enhancements to many package components, so if I am going to use iRedMail, I don't really want to downgrade.  Unfortunately the install bombs with many dependency conflicts, please see below and advise?  I have the default repos and added one for universal to fix the inability to install dialog initially, but still ran into this AFTER getting through the wizard:

[ INFO ] Use config file: /home/haynes/iRedMail-0.9.8/config for mail server setting.
[ INFO ] Import installation process status from file: /home/haynes/iRedMail-0.9.8/runtime/install.status.
[ INFO ] Add apt repo for SOGo: https://packages.inverse.ca
[ INFO ] Import apt key (0x810273C4) for SOGo repo (https://packages.inverse.ca).
Executing: /tmp/apt-key-gpghome.C2QdYJtzzL/gpg.1.sh --keyserver keys.gnupg.net --recv-key 0x810273C4
gpg: key 19CDA6A9810273C4: "Inverse Support (package signing) <support@inverse.ca>" not changed
gpg: Total number processed: 1
gpg:              unchanged: 1
[ INFO ] Resynchronizing the package index files (apt-get update) ...
Hit:1 http://us.archive.ubuntu.com/ubuntu bionic InRelease
Hit:2 https://packages.inverse.ca/SOGo/nightly/4/ubuntu bionic InRelease
Hit:3 http://archive.ubuntu.com/ubuntu bionic InRelease
Hit:4 http://archive.ubuntu.com/ubuntu bionic-security InRelease
Hit:5 http://archive.ubuntu.com/ubuntu bionic-updates InRelease
Reading package lists... Done
[ INFO ] Installing package(s): postfix postfix-pcre libsasl2-modules postfix-ldap slapd ldap-utils libnet-ldap-perl libdbd-mysql-perl mysql-server mysql-client php-cli php-fpm php-json php-gd php-curl mcrypt php-intl php-xml php-mbstring php-ldap php-mysql nginx-full dovecot-imapd dovecot-pop3d dovecot-lmtpd dovecot-managesieved dovecot-sieve dovecot-ldap dovecot-mysql amavisd-new libcrypt-openssl-rsa-perl libmail-dkim-perl clamav-freshclam clamav-daemon spamassassin altermime arj nomarch cpio lzop cabextract p7zip-full rpm ripole libmail-spf-perl unrar-free pax lrzip mlmmj php-net-ldap3 sogo sogo-activesync sope4.9-gdl1-mysql python-sqlalchemy python-dnspython python-ldap python-mysqldb python-pymysql python-jinja2 python-netifaces python-webpy python-beautifulsoup python-lxml python-pycurl python-requests uwsgi uwsgi-plugin-python python-bcrypt fail2ban zlib1g libuuid1 libmnl0 curl lm-sensors netcat bzip2 acl patch cron tofrodos logwatch unzip bsdutils liblz4-tool
Reading package lists...
Building dependency tree...
Reading state information...
acl is already the newest version (2.2.52-3build1).
bzip2 is already the newest version (1.0.6-8.1).
cpio is already the newest version (2.12+dfsg-6).
cron is already the newest version (3.0pl1-128.1ubuntu1).
libmnl0 is already the newest version (1.0.4-2).
libsasl2-modules is already the newest version (2.1.27~101-g0780600+dfsg-3ubuntu2).
patch is already the newest version (2.7.6-2ubuntu1).
zlib1g is already the newest version (1:1.2.11.dfsg-0ubuntu2).
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
dovecot-ldap : Depends: dovecot-core (= 1:2.2.33.2-1ubuntu4) but 1:2.2.33.2-1ubuntu4.1 is to be installed
dovecot-lmtpd : Depends: dovecot-core (= 1:2.2.33.2-1ubuntu4) but 1:2.2.33.2-1ubuntu4.1 is to be installed
dovecot-mysql : Depends: dovecot-core (= 1:2.2.33.2-1ubuntu4) but 1:2.2.33.2-1ubuntu4.1 is to be installed
nginx-full : Depends: libnginx-mod-http-auth-pam (= 1.14.0-0ubuntu1) but it is not going to be installed
              Depends: libnginx-mod-http-dav-ext (= 1.14.0-0ubuntu1) but it is not going to be installed
              Depends: libnginx-mod-http-echo (= 1.14.0-0ubuntu1) but it is not going to be installed
              Depends: libnginx-mod-http-geoip (= 1.14.0-0ubuntu1) but 1.14.0-0ubuntu1.2 is to be installed
              Depends: libnginx-mod-http-image-filter (= 1.14.0-0ubuntu1) but 1.14.0-0ubuntu1.2 is to be installed
              Depends: libnginx-mod-http-subs-filter (= 1.14.0-0ubuntu1) but it is not going to be installed
              Depends: libnginx-mod-http-upstream-fair (= 1.14.0-0ubuntu1) but it is not going to be installed
              Depends: libnginx-mod-http-xslt-filter (= 1.14.0-0ubuntu1) but 1.14.0-0ubuntu1.2 is to be installed
              Depends: libnginx-mod-mail (= 1.14.0-0ubuntu1) but 1.14.0-0ubuntu1.2 is to be installed
              Depends: libnginx-mod-stream (= 1.14.0-0ubuntu1) but 1.14.0-0ubuntu1.2 is to be installed
              Depends: nginx-common (= 1.14.0-0ubuntu1) but 1.14.0-0ubuntu1.2 is to be installed
php-fpm : Depends: php7.2-fpm but it is not going to be installed
php-intl : Depends: php7.2-intl but it is not going to be installed
php-mbstring : Depends: php7.2-mbstring but it is not going to be installed
sogo : Depends: gnustep-make but it is not going to be installed
E: Unable to correct problems, you have held broken packages.