This document will explain the process of installing
a fully working virtual email system on CentOS Linux using PostFix and
Dovecot. I personally finalized my setup with RoundCube Webmail Project
for robust online email usage. This how-to is very simple and easy to
implement for beginners.
INSTALLATION NOTES
If
you have not installed the packages this would be a good time to get
moving. Using CentOS or RedHat Enterprise Linux (RHEL) you can use the
“YUM” package manager to achieve this. You can also remove
sendmail because it may cause SMTP based port issues with Postfix.
Installing Postfix with database support is a bit tricky. You have to
enable the CentOS Plus repository. You will then use upgrade if already
installed or install for a full fresh install. I had to use upgrade due
to installing the normal Postfix later finding out it would not work
with this setup due to the lack of MySQL database support.
yum --enablerepo=centosplus upgrade/install postfix* yum install dovecot |
Note: You
don't want to screw up your PostFix install with yum
updates! Here is how to setup /etc/yum.repos.d/CentOS-Base.repo:
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
#baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
includepkgs=postfix-*
exclude=postfix-*plus*
You
would also want to add this to both the [base] and [update] sections of
/etc/yum.repos.d/CentOS-Base.repo, so as not to get postfix packages
from there anymore:
exclude=postfix-*
If
you had everything working and all of a sudden your SMTP is broke or
you have error like "unsupported dictionary type: mysql" check this out for a nice easy fix.
DATABASE
The
next step is to manually create the blank database with a corresponding
user. You need to log into MySQL and create the database using the
create database command. Then, give your new user permissions to that
database. In this example the user is named mail with a password of
mail.
mysql -uroot –p CREATE DATABASE mail; GRANT ALL PRIVILEGES ON mail.* TO 'mail'@'localhost' IDENTIFIED BY 'mail'; quit |
The
next step is to prepare the database. In this example we use MySQL with
the PostFix Admin database dump provided with PostFix Admin files.
Note the URL might change based on version. Extract the files to
your web folder unless you plan on administering your email accounts
manually. Something like phpMyAdmin would work as well once you
understand the required table data.
wget http://sourceforge.net/projects/postfixadmin/ tar xvfz postfixadmin-2.1.0.tgz |
Open
postfixadmin-2.1.0/DATABASE_MYSQL.TXT with your favorite editor such as
vim, nano or gedit and comment out or remove all lines under create
user section Postfix / MySQL, since we have created our own use for the
mail server. When this is done, just load the file into MySQL using the
following command.
mysql -umail -p mail < postfixadmin-2.1.0/DATABASE_MYSQL.TXT |
DOVECOT
Open up your Dovecot.conf for editing. The sample
below is what I used to create this system using IMAP for webmail and
POP3 for email clients like Outlook or Thunderbird direct access.
base_dir = /var/run/dovecot/
protocols = imap pop3
protocol imap {
listen = *:143
}
protocol pop3 {
listen = *:110
}
log_timestamp = "%Y-%m-%d %H:%M:%S"
syslog_facility = mail
mail_location = maildir:/var/vmail/%d/%u
mail_extra_groups = mail
mail_debug = no
first_valid_uid = 150
last_valid_uid = 150
maildir_copy_with_hardlinks = yes
protocol imap {
login_executable = /usr/libexec/dovecot/imap-login
mail_executable = /usr/libexec/dovecot/imap
imap_max_line_length = 65536
}
protocol pop3 {
login_executable = /usr/libexec/dovecot/pop3-login
mail_executable = /usr/libexec/dovecot/pop3
pop3_uidl_format = %08Xu%08Xv
}
protocol lda {
postmaster_address =sendmail_path = /usr/lib/sendmail
auth_socket_path = /var/run/dovecot/auth-master
}
auth_verbose = no
auth_debug = no
auth_debug_passwords = no
auth default {
mechanisms = plain
passdb sql {
args = /etc/dovecot/dovecot-sql.conf
}
userdb sql {
args = /etc/dovecot/dovecot-sql.conf
}
user = nobody
socket listen {
master {
path = /var/run/dovecot/auth-master
mode = 0660
user = vmail
group = mail
}
client {
path = /var/spool/postfix/private/auth
mode = 0660
user = postfix
group = postfix
}
}
}
Open
up the dovecot-sql.conf for editing. This file has been specified in
the main Dovecot configuration file. Dovecot looks for this file in
order to fire up the database driven virtual mailboxes.
driver = mysql connect = host=localhost dbname=mail user=mail password=mail default_pass_scheme = MD5 user_query
quota FROM mailbox WHERE username = '%u' AND active = '1' password_query
userdb_uid, 12 as userdb_gid FROM mailbox WHERE username = '%u' AND active = '1' |
POSTFIX
Open
Main.cf for editing. You will need to change “hostname” and
“myorigin”. The rest was simple and should work on almost
all systems for simple implementation.
biff = no append_dot_mydomain = no #delay_warning_time = 4h myhostname = yourhostnamehere like mail.domain.com myorigin = 192.168.1.1 mydestination = localhost relayhost = alias_maps = hash:/etc/aliases mynetworks = 127.0.0.0/8 mailbox_size_limit = 0 recipient_delimiter = + inet_interfaces = all smtp_helo_name = $myhostname # Virtual mailbox settings virtual_mailbox_domains = proxy:mysql:$config_directory/mysql_virtual_domains_maps.cf virtual_mailbox_base = /var/vmail virtual_mailbox_maps = proxy:mysql:$config_directory/mysql_virtual_mailbox_maps.cf virtual_alias_maps = proxy:mysql:$config_directory/mysql_virtual_alias_maps.cf virtual_minimum_uid = 150 virtual_uid_maps = static:150 virtual_gid_maps = static:12 virtual_transport = dovecot dovecot_destination_recipient_limit = 1 # SASL Authentication smtpd_sasl_auth_enable = yes smtpd_sasl_exceptions_networks = $mynetworks smtpd_sasl_security_options = noanonymous broken_sasl_auth_clients = yes smtpd_sasl_type = dovecot smtpd_sasl_path = private/auth smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, permit |
Open
master.cf for editing. Add these two lines to the bottom of the file. I
found that if the proper spacing and formatting was not found Postfix
would actually not start properly. So as a tip check these lines for
proper spacing and formatting as a trouble shooting step.
dovecot flags=DRhu user=vmail:mail argv=/usr/libexec/dovecot/deliver -d $(recipient) |
Add file mysql_virtual_alias_maps.cf and open for editing.
user = mail password = mail hosts = localhost dbname = mail table = alias select_field = goto where_field = address additional_conditions = and active = '1' #query = SELECT goto FROM alias WHERE address='%s' AND active = '1' |
Add file mysql_virtual_domains_maps.cf and open for editing.
user = mail password = mail hosts = localhost dbname = mail table = domain select_field = domain where_field = domain additional_conditions = and backupmx = '0' and active = '1' #query = SELECT domain FROM domain WHERE domain='%s' AND backupmx = '0' AND active = '1' |
Add file mysql_virtual_mailbox_limit_maps.cf and open for editing.
user = mail password = mail hosts = localhost dbname = mail table = mailbox select_field = quota where_field = username additional_conditions = and active = '1' #query = SELECT quota FROM mailbox WHERE username='%s' AND active = '1' |
Add file mysql_virtual_mailbox_maps.cf and open for editing.
user = mail password = mail hosts = localhost dbname = mail table = mailbox select_field = CONCAT(domain,'/',maildir) where_field = username additional_conditions = and active = '1' #query = SELECT CONCAT(domain,'/',maildir) FROM mailbox WHERE username='%s' AND active = '1' |
ADMINISTRATION
I
have installed phpMyAdmin as well as Postfix Admin. Between the two
packages I was able to learn how to create mailboxes manually, if
needed. I suggest you start with tools like Postfix Admin until you
fully understand what data is required for your email system to
function properly.
WEBMAIL
I
decided to go with RoundCube Webmail Project due to the sleek look and
feel. Once downloaded and extracted it took all of 15 minutes to have
it up and running for all users globally. If you want to really seal
the deal create a virtual host within Apache to handle webmail.* for
all of your domains. This really gives it a professional touch for your
end users.
CONCLUSION
Since
installing the system I have had no issues with many domains containing
multiple virtual user mailboxes. This is a great virtual setup and can
easily go hand in hand with my virtual ftp documentation posted
earlier. Once you have these down, you can easily add virtual hosts in
Apache for a robust hosting solution at no required software cost.
REFERENCE
http://www.chrisgountanis.com/technical/34-technical/59-isp-style-virtual-mail-system.html
