I installed in on a fresh ubuntu 14.04, and got this error on apache2

* Starting web server apache2                                                                                                                                 *
* The apache2 configtest failed.
Output of config test was:
AH00526: Syntax error on line 27 of /etc/apache2/sites-enabled/default-ssl.conf:
Invalid command 'Header', perhaps misspelled or defined by a module not included in the server configuration
Action 'configtest' failed.
The Apache error log may have more information.

EDIT:

Fixed it by running `a2enmod headers` and restarting apache2

[ INFO ] Configure LDAP server: OpenLDAP.
cp: missing destination file operand after `/etc/openldap/schema/amavisd-new.schema'
Try `cp --help' for more information.
[ INFO ] Setup daily cron job to backup LDAP data with /var/vmail/backup/backup_openldap.sh
[ INFO ] Configure MySQL database server.
[ INFO ] Setup daily cron job to backup SQL databases with /var/vmail/backup/backup_mysql.sh
[ INFO ] Configure Postfix (Message Transfer Agent).
[ INFO ] Configure Dovecot (pop3/imap/managesieve server).
[ INFO ] Configure ClamAV (anti-virus toolkit).
usermod: user 'amavis' does not exist
chmod: cannot access `/var/spool/amavisd/tmp': No such file or directory
chmod: cannot access `/var/spool/amavisd/quarantine': No such file or directory
[ INFO ] Configure Amavisd-new (interface between MTA and content checkers).
chgrp: invalid group: `amavis'
chmod: cannot access `/etc/amavisd/amavisd.conf': No such file or directory
chmod: cannot access `/etc/amavisd/amavisd.conf': No such file or directory
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
sed: can't read /etc/amavisd/amavisd.conf: No such file or directory
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 140: /etc/amavisd/amavisd.conf: No such file or directory
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 148: /etc/amavisd/amavisd.conf: No such file or directory
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 258: /etc/amavisd/amavisd.conf: No such file or directory
chown: invalid user: `amavis:amavis'
chown: invalid user: `amavis:amavis'
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 38: /etc/amavisd/amavisd.conf: No such file or directory
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 349: /etc/amavisd/amavisd.conf: No such file or directory
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 388: /etc/amavisd/amavisd.conf: No such file or directory
Can't open /usr/sbin/amavisd: No such file or directory.
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 416: /etc/amavisd/amavisd.conf: No such file or directory
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 434: /etc/amavisd/amavisd.conf: No such file or directory
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 442: /etc/amavisd/amavisd.conf: No such file or directory
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 451: /etc/amavisd/amavisd.conf: No such file or directory
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 480: /etc/amavisd/amavisd.conf: No such file or directory
/root/distr/iRedMail-0.9.3/functions/amavisd.sh: line 494: /etc/amavisd/amavisd.conf: No such file or directory
Can't open /etc/amavisd/amavisd.conf: No such file or directory.
[ INFO ] Configure SpamAssassin (content-based spam filter).
[ INFO ] Configure iRedAPD (postfix policy daemon).
[ INFO ] Configure iRedAdmin (official web-based admin panel).
[ INFO ] Configure Fail2ban (authentication failure monitor).
[ INFO ] Configure Roundcube webmail.
[ INFO ] Configure Awstats (logfile analyzer for mail and web server).

*************************************************************************
* iRedMail-0.9.3 installation and configuration complete.
*************************************************************************

[ INFO ] Disable SELinux in /etc/selinux/config.
< Question > Would you like to use firewall rules provided by iRedMail?
< Question > File: /etc/sysconfig/iptables, with SSHD port: 22. [Y|n]

Maybe smth is wrong in install script?

No configuration sogo in Apache 2.4 on FreeBSD 10.2

Please, put this information to http://www.iredmail.org/download.html

Just soo this:

Cent OS 7 ... minimal install
and installing iredmail

* Storage base directory:               /var/vmail
* Mailboxes:                            /var/vmail/vmail1
* Daily backup of SQL/LDAP databases:   /var/vmail/backup
* Store mail accounts in:               OpenLDAP
* Web server:                           Apache
* First mail domain name:               xxxx.hr
* Mail domain admin:                    xxxxx@xxxx.hr
* Additional components:                iRedAdmin Roundcubemail SOGo Awstats Fail2ban

< Question > Continue? [y|N]y
/root/iRedMail-0.9.3/functions/packages.sh: line 60: perl: command not found
[ INFO ] Add yum repo for SOGo: /etc/yum.repos.d/sogo.repo.

i use ubuntu server 14.04.3 ?? download iRedMail-0.9.3 ??

thanks a lot for the great job ZHB. 
About the small installation glitch on OpenBSD 5.8:  the MD5 checksumming of the iredmail components still fails with your most recent tarball, because there is no md5sum on OpenBSD, only the command md5.
Very simple and trivial, I changed in get_all.sh line 136:
md5sum -c ${MD5_FILE}
with
md5 -c ${MD5_FILE}

(but of course should be fixed with an extra if/fi specific to OpenBSD to keep get_all.sh working elsewhere than on OpenBSD).

I had trouble with upgrade_iredapd.sh in line 404 as I decided not to install iRedAdmin (open source edition) in the initial setup:

-i used with no filenames on the command line, reading from STDIN.

I skipped this command.

Also I couldn't "Migrate Cluebringer to iRedAPD" as there's not cluebringer-database present on my system - the version of the initial setup was 0.9.2. Are the greylisting and throttling settings now missing on my system completely or did I just skip the migration of user defined setting I didn't had?

Nevertheless: Great upgrade instructions, thanks for the work!

This is a bug in tools/upgrade_iredapd.sh, caused by incorrect variable name (IREDADMIN_CONF_PY should be IREDAPD_CONF_PY). It's safe to skip it if you don't have iRedAdmin.

If you didn't run Cluebringer, it's ok to skip the migration.

Hello Zhang , gr8 work
I have iredmail-0.9.2 with IredAdmin Pro , Ubuntu 14.04 LTS
upgrade is working for Ubuntu 14.04 ??

hello ZhangHuangbin !! Once installed , the installation is complete iredmail 0.9.3 . I visited 192.168.1.100 (ip static address) then display 404 Not Found . but 0.9.2 then display web mail...

First of all Thanks!

When following this : Web server: Enable HSTS (HTTP Strict Transport Security) support
I encountered the following error on Apache 2 in Ubuntu:

If you encounter this, the headers module of Apache2 isn't installed

This is easy to resolve :
(install the headers mod for Apache2)
sudo a2enmod headers

Next you need to restart Apache2

sudo service apache2 restart

That's it. Now it will work.