==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.2.1
- Deployed with iRedMail Easy or the downloadable installer? Yes, failure is during script iRedMail.sh
- Linux/BSD distribution name and version: Ubuntu 18.04 LTS - nothing else installed full package updates installed using apt-get
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): mysql, but the installer failed before we got there.
- Web server (Apache or Nginx): WIll set for apache if installer allows, but will use nginx if only option
- Manage mail accounts with iRedAdmin-Pro? Yes, I have purchased it, but the iRedMain.sh installer is failing
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.

Log follows

====

I am having this exact problem with version 1.2.1 on Ubuntu 18.04 The tarballs will not download with wget, but I can use the link to download manually from my machine on a home network.

Here is error from script. I am running as root.
:~/iRedMail-1.2.1# bash ./iRedMail.sh
< SKIP > Function: check_new_iredmail.
[ INFO ] apt update ...
Hit:1 http://archive.ubuntu.com/ubuntu bionic InRelease
Get:2 http://security.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB]
Get:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]           
Get:4 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB]                     
Get:5 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages [969 kB]
Get:6 http://archive.ubuntu.com/ubuntu bionic-updates/universe amd64 Packages [1081 kB]
Fetched 2302 kB in 1s (1828 kB/s)                         
Reading package lists... Done
'multiverse' distribution component is already enabled for all sources.
[ INFO ] Fetching source tarballs ...
[ INFO ] + 1 of 6: https://dl.iredmail.org/yum/misc/iRedAdmin-1.0.tar.bz2
[ INFO ] + 2 of 6: https://dl.iredmail.org/yum/misc/mlmmjadmin-2.1.tar.gz
[ INFO ] + 3 of 6: https://dl.iredmail.org/yum/misc/iRedAPD-3.6.tar.gz
[ INFO ] + 4 of 6: https://dl.iredmail.org/yum/misc/netdata-v1.21.1.gz.run
[ INFO ] + 5 of 6: https://dl.iredmail.org/yum/misc/roundc … ete.tar.gz
[ INFO ] + 6 of 6: https://dl.iredmail.org/yum/misc/webpy-0.51.tar.gz
[ INFO ] Validate downloaded source tarballs ...
sha256sum: misc/iRedAdmin-1.0.tar.bz2: No such file or directory
misc/iRedAdmin-1.0.tar.bz2: FAILED open or read
sha256sum: misc/mlmmjadmin-2.1.tar.gz: No such file or directory
misc/mlmmjadmin-2.1.tar.gz: FAILED open or read
sha256sum: misc/iRedAPD-3.6.tar.gz: No such file or directory
misc/iRedAPD-3.6.tar.gz: FAILED open or read
sha256sum: misc/netdata-v1.21.1.gz.run: No such file or directory
misc/netdata-v1.21.1.gz.run: FAILED open or read
sha256sum: misc/roundcubemail-1.4.6-complete.tar.gz: No such file or directory
misc/roundcubemail-1.4.6-complete.tar.gz: FAILED open or read
sha256sum: misc/webpy-0.51.tar.gz: No such file or directory
misc/webpy-0.51.tar.gz: FAILED open or read
sha256sum: WARNING: 6 listed files could not be read
    [ FAILED ]
<< ERROR >> Package verification failed. Script exit ...

Here is the manual wget results. I have tried all 6 files.
:~$ wget https://dl.iredmail.org/yum/misc/iRedAPD-3.6.tar.bz2
--2020-06-10 18:22:32--  https://dl.iredmail.org/yum/misc/iRedAPD-3.6.tar.bz2
Resolving dl.iredmail.org (dl.iredmail.org)... 139.162.146.87
Connecting to dl.iredmail.org (dl.iredmail.org)|139.162.146.87|:443... failed: Connection timed out.
Retrying.

This will try forever.

I can download the files from my machine on my home network.

I cannot ping dl.iredmail.org from this machine, but I can ping it from my home machine.
I had the network engineers temporarily give your host 139.162.146.87 full firewall access. Nothing.

I can ping google and all our public nameservers, but not your host. But I can ping it from my home

Is it possible that our net is blocked 172.84.144.0/24?