There is a new revision of this tutorial available for CentOS 6.3.

Virtual Users And Domains With Postfix, Courier, MySQL And SquirrelMail (CentOS 6.2 x86_64)

Version 1.0
Author: Falko Timme
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This tutorial is Copyright (c) 2012 by Falko Timme. It is derived from a tutorial from Christoph Haas which you can find at You are free to use this tutorial under the Creative Commons license 2.5 or any later version.

This document describes how to install a Postfix mail server that is based on virtual users and domains, i.e. users and domains that are in a MySQL database. I'll also demonstrate the installation and configuration of Courier (Courier-POP3, Courier-IMAP), so that Courier can authenticate against the same MySQL database Postfix uses.

The resulting Postfix server is capable of SMTP-AUTH and TLS and quota (quota is not built into Postfix by default, I'll show how to patch your Postfix appropriately). Passwords are stored in encrypted form in the database (most documents I found were dealing with plain text passwords which is a security risk). In addition to that, this tutorial covers the installation of Amavisd, SpamAssassin and ClamAV so that emails will be scanned for spam and viruses. I will also show how to install SquirrelMail as a webmail interface so that users can read and send emails and change their passwords.

The advantage of such a "virtual" setup (virtual users and domains in a MySQL database) is that it is far more performant than a setup that is based on "real" system users. With this virtual setup your mail server can handle thousands of domains and users. Besides, it is easier to administrate because you only have to deal with the MySQL database when you add new users/domains or edit existing ones. No more postmap commands to create db files, no more reloading of Postfix, etc. For the administration of the MySQL database you can use web based tools like phpMyAdmin which will also be installed in this howto. The third advantage is that users have an email address as user name (instead of a user name + an email address) which is easier to understand and keep in mind.

This howto is meant as a practical guide; it does not cover the theoretical backgrounds. They are treated in a lot of other documents in the web.

This document comes without warranty of any kind! I want to say that this is not the only way of setting up such a system. There are many ways of achieving this goal but this is the way I take. I do not issue any guarantee that this will work for you!


1 Preliminary Note

This tutorial is based on CentOS 6.2 x86_64, so you should set up a basic CentOS 6.2 server installation before you continue with this tutorial (e.g. as shown in the first six chapters of The Perfect Server - CentOS 6.2 x86_64 With Apache2 [ISPConfig 3]). The system should have a static IP address. I use as my IP address in this tutorial and as the hostname.

You should make sure that the firewall is off (at least for now) and that SELinux is disabled (this is important!).


2 Enable Additional Repositories And Install Some Software

First we import the GPG keys for software packages:

rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY*

Then we enable the RPMforge and EPEL repositories on our CentOS system as lots of the packages that we are going to install in the course of this tutorial are not available in the official CentOS 6.2 repositories:

rpm --import

cd /tmp
rpm -ivh rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm

(If the above link doesn't work anymore, you can find the current version of rpmforge-release here:

rpm --import
rpm -ivh epel-release-6-5.noarch.rpm

yum install yum-priorities

Edit /etc/yum.repos.d/epel.repo...

vi /etc/yum.repos.d/epel.repo

... and add the line priority=10 to the [epel] section:

name=Extra Packages for Enterprise Linux 6 - $basearch

Then we update our existing packages on the system:

yum update

Now we install some software that we need later on:

yum groupinstall 'Development Tools'


3 Install Apache, MySQL, phpMyAdmin

This can all be installed with one single command (including the packages we need to build Courier-IMAP):

yum install ntp httpd mysql-server php php-mysql php-mbstring rpm-build gcc mysql-devel openssl-devel cyrus-sasl-devel pkgconfig zlib-devel phpMyAdmin pcre-devel openldap-devel postgresql-devel expect libtool-ltdl-devel openldap-servers libtool gdbm-devel pam-devel gamin-devel libidn-devel db4-devel mod_ssl telnet


4 Install Courier-IMAP, Courier-Authlib, And Maildrop

Unfortunately there are no rpm packages for Courier-IMAP, Courier-Authlib, and Maildrop, therefore we have to build them ourselves.

RPM packages should not be built as root; courier-imap will even refuse to compile if it detects that the compilation is run as the root user. Therefore we create a normal user account now (falko in this example) and give him a password:

useradd -m -s /bin/bash falko
passwd falko

We will need the sudo command later on so that the user falko can compile and install the rpm packages. But first, we must allow falko to run all commands using sudo:



In the file that opens there's a line root ALL=(ALL) ALL. Add a similar line for falko just below that line:

## Allow root to run any commands anywhere
root ALL=(ALL) ALL
falko ALL=(ALL) ALL

Now we are ready to build our rpm package. First become the user falko:

su falko

Next we create our build environment:

mkdir $HOME/rpm
mkdir $HOME/rpm/SOURCES
mkdir $HOME/rpm/SPECS
mkdir $HOME/rpm/BUILD
mkdir $HOME/rpm/SRPMS
mkdir $HOME/rpm/RPMS
mkdir $HOME/rpm/RPMS/i386
mkdir $HOME/rpm/RPMS/x86_64

echo "%_topdir $HOME/rpm" >> $HOME/.rpmmacros

Now we create a downloads directory and download the source files from

mkdir $HOME/downloads
cd $HOME/downloads


(Please note that I use Courier-IMAP 4.9.3 here instead of the newer 4.10.0 because 4.10.0 depends on systemctl which exists for Fedora, but not for CentOS.)

Now (still in $HOME/downloads) we can build courier-authlib:

sudo rpmbuild -ta courier-authlib-0.63.0.tar.bz2

After the build process, the rpm packages can be found in /root/rpmbuild/RPMS/x86_64 (/root/rpmbuild/RPMS/i386 if you are on an i386 system). The command

sudo ls -l /root/rpmbuild/RPMS/x86_64

shows you the available rpm packages:

[[email protected] downloads]$ sudo ls -l /root/rpmbuild/RPMS/x86_64
total 528
-rw-r--r-- 1 root root 124032 Jan 26 17:09 courier-authlib-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root 270900 Jan 26 17:09 courier-authlib-debuginfo-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  35068 Jan 26 17:09 courier-authlib-devel-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  17372 Jan 26 17:09 courier-authlib-ldap-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  13928 Jan 26 17:09 courier-authlib-mysql-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  13080 Jan 26 17:09 courier-authlib-pgsql-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root   8316 Jan 26 17:09 courier-authlib-pipe-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  34068 Jan 26 17:09 courier-authlib-userdb-0.63.0-1.el6.x86_64.rpm
[[email protected] downloads]$

Select the ones you want to install, and install them like this:

sudo rpm -ivh /root/rpmbuild/RPMS/x86_64/courier-authlib-0.63.0-1.el6.x86_64.rpm /root/rpmbuild/RPMS/x86_64/courier-authlib-mysql-0.63.0-1.el6.x86_64.rpm /root/rpmbuild/RPMS/x86_64/courier-authlib-devel-0.63.0-1.el6.x86_64.rpm

Now we go back to our downloads directory:

cd $HOME/downloads

Run the following commands to create required directories/change directory permissions (because otherwise the build process for Courier-Imap will fail):

sudo mkdir -p /var/cache/ccache/tmp
sudo chmod o+rwx /var/cache/ccache/
sudo chmod 777 /var/cache/ccache/tmp

Now run rpmbuild again, this time without sudo, otherwise the compilation will fail because it was run as root:

rpmbuild -ta courier-imap-4.9.3.tar.bz2

After the build process, the rpm packages can be found in $HOME/rpm/RPMS/x86_64 ($HOME/rpm/RPMS/i386 if you are on an i386 system):

cd $HOME/rpm/RPMS/x86_64

The command

ls -l

shows you the available rpm packages:

[[email protected] x86_64]$ ls -l
total 1088
-rw-r--r-- 1 falko falko 333540 Jan 26 17:27 courier-imap-4.9.3-1.x86_64.rpm
-rw-r--r-- 1 falko falko 776100 Jan 26 17:27 courier-imap-debuginfo-4.9.3-1.x86_64.rpm
[[email protected] x86_64]$ 

You can install courier-imap like this:

sudo rpm -ivh courier-imap-4.9.3-1.x86_64.rpm

Now we go back to our downloads directory:

cd $HOME/downloads

and run rpmbuild again, this time to build a maildrop package:

sudo rpmbuild -ta maildrop-2.5.5.tar.bz2

After the build process, the rpm packages can be found in /root/rpmbuild/RPMS/x86_64 (/root/rpmbuild/RPMS/i386 if you are on an i386 system). The command

sudo ls -l /root/rpmbuild/RPMS/x86_64

shows you the available rpm packages:

[[email protected] downloads]$ sudo ls -l /root/rpmbuild/RPMS/x86_64
total 1712
-rw-r--r-- 1 root root 124032 Jan 26 17:09 courier-authlib-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root 270900 Jan 26 17:09 courier-authlib-debuginfo-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  35068 Jan 26 17:09 courier-authlib-devel-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  17372 Jan 26 17:09 courier-authlib-ldap-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  13928 Jan 26 17:09 courier-authlib-mysql-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  13080 Jan 26 17:09 courier-authlib-pgsql-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root   8316 Jan 26 17:09 courier-authlib-pipe-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  34068 Jan 26 17:09 courier-authlib-userdb-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root 286480 Jan 26 17:32 maildrop-2.5.5-1.x86_64.rpm
-rw-r--r-- 1 root root 751348 Jan 26 17:32 maildrop-debuginfo-2.5.5-1.x86_64.rpm
-rw-r--r-- 1 root root 102108 Jan 26 17:32 maildrop-devel-2.5.5-1.x86_64.rpm
-rw-r--r-- 1 root root  65940 Jan 26 17:32 maildrop-man-2.5.5-1.x86_64.rpm
[[email protected] downloads]$

You can now install maildrop like this:

sudo rpm -ivh /root/rpmbuild/RPMS/x86_64/maildrop-2.5.5-1.x86_64.rpm

After you have compiled and installed all needed packages, you can become root again by typing



5 Apply Quota Patch To Postfix

We have to get the Postfix source rpm, patch it with the quota patch, build a new Postfix rpm package and install it.

cd /usr/src
rpm -ivh postfix-2.6.6-2.2.el6_1.src.rpm

The last command will show some warnings that you can ignore:

warning: user mockbuild does not exist - using root
warning: group mockbuild does not exist - using root

cd /root/rpmbuild/SOURCES
gunzip postfix-2.6.5-vda-ng.patch.gz
cd /root/rpmbuild/SPECS/

Now we must edit the file postfix.spec:

vi postfix.spec

Add Patch0: postfix-2.6.5-vda-ng.patch to the # Patches stanza, and %patch0 -p1 -b .vda-ng to the %setup -q stanza:

# Patches Patch0: postfix-2.6.5-vda-ng.patch Patch1: postfix-2.6.1-config.patch Patch2: postfix-2.6.1-files.patch Patch3: postfix-alternatives.patch Patch8: postfix-large-fs.patch Patch9: pflogsumm-1.1.1-datecalc.patch Patch10: postfix-2.6.6-CVE-2011-0411.patch Patch11: postfix-2.6.6-CVE-2011-1720.patch
%prep %setup -q # Apply obligatory patches %patch0 -p1 -b .vda-ng %patch1 -p1 -b .config %patch2 -p1 -b .files %patch3 -p1 -b .alternatives %patch8 -p1 -b .large-fs

Then we build our new Postfix rpm package with quota and MySQL support:

rpmbuild -ba postfix.spec

Our Postfix rpm package is created in /root/rpmbuild/RPMS/x86_64 (/root/rpmbuild/RPMS/i386 if you are on an i386 system), so we go there:

cd /root/rpmbuild/RPMS/x86_64

The command

ls -l

shows you the available packages:

[[email protected] x86_64]# ls -l
total 10728
-rw-r--r-- 1 root root  124032 Jan 26 17:09 courier-authlib-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  270900 Jan 26 17:09 courier-authlib-debuginfo-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root   35068 Jan 26 17:09 courier-authlib-devel-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root   17372 Jan 26 17:09 courier-authlib-ldap-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root   13928 Jan 26 17:09 courier-authlib-mysql-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root   13080 Jan 26 17:09 courier-authlib-pgsql-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root    8316 Jan 26 17:09 courier-authlib-pipe-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root   34068 Jan 26 17:09 courier-authlib-userdb-0.63.0-1.el6.x86_64.rpm
-rw-r--r-- 1 root root  286480 Jan 26 17:32 maildrop-2.5.5-1.x86_64.rpm
-rw-r--r-- 1 root root  751348 Jan 26 17:32 maildrop-debuginfo-2.5.5-1.x86_64.rpm
-rw-r--r-- 1 root root  102108 Jan 26 17:32 maildrop-devel-2.5.5-1.x86_64.rpm
-rw-r--r-- 1 root root   65940 Jan 26 17:32 maildrop-man-2.5.5-1.x86_64.rpm
-rw-r--r-- 1 root root 2139072 Jan 26 17:44 postfix-2.6.6-2.2.el6.x86_64.rpm
-rw-r--r-- 1 root root 7021608 Jan 26 17:44 postfix-debuginfo-2.6.6-2.2.el6.x86_64.rpm
-rw-r--r-- 1 root root   61768 Jan 26 17:44 postfix-perl-scripts-2.6.6-2.2.el6.x86_64.rpm
[[email protected] x86_64]# 

To make sure that no version of postfix was previously installed on your system, use:

yum remove postfix

Pick the Postfix package and install it like this:

rpm -ivh postfix-2.6.6-2.2.el6.x86_64.rpm

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6 Comment(s)

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From: Habeeb

Dear Admin,

 I am getting this below error while building the rpm for postfix, so please advice what i should now??? Still i am in the first page.


[[email protected] SPECS]# rpmbuild -ba postfix.spec
error: Name field must be present in package: (main package)
error: Version field must be present in package: (main package)
error: Release field must be present in package: (main package)
error: Summary field must be present in package: (main package)
error: License field must be present in package: (main package)
[[email protected] SPECS]#

From: Arash S.

Hi there,

the download address for epel has been changed. it is: ""



From: Anonymous

 "epel-release-6-5.noarch.rpm" is not there / anymore. 

Try this instead: 



From: Hillary John


From: Skaroth

Thank you for this great tutorial. Perfectly written!

From: Alberto


 Thanks for this great HowTo.

 I´m trying to adapt this installation to use with  postfixadmin, but i´m having a lot of problems, could anybody let a link to a HowTo or something like that?


Thanks a lot.