How to set up a mail server with PostfixAdmin on CentOS 7

In this article, we will show you how to setup and configure a mail server with PostfixAdmin, Postfix, Dovecot and SQLite on a CentOS VPS. PostfixAdmin is a PHP-based web front-end that allows you to manage virtual domains and users for a Postfix mail transport agent. This guide should work on other Linux VPS systems as well but was tested and written for a CentOS 7 VPS.

If you use Ubuntu, follow our tutorial to set up Postfix, Dovecot, Spamassassin, SQLite and PostfixAdmin on an Ubuntu 16.04 VPS with Nginx and PHP 7.0

1. Update the system and install necessary packages

yum update 
yum install wget nano sqlite

2. Create system user

For security reasons, we will create a new system user who will be the owner of all mailboxes.

useradd -r -u 150 -g mail -d /var/vmail -s /sbin/nologin -c "Virtual Mail User" vmail
mkdir -p /var/vmail
chmod -R 770 /var/vmail
chown -R vmail:mail /var/vmail

3. Install PostfixAdmin

The latest version of PostfixAdmin, version 3, supports MySQL, PostgreSQL, and SQLite databases. In this guide, we will use SQLite.
Download the PostfixAdmin archive from SourceForge and extract it in the /var/www/html/ directory:

wget -q -O - "http://downloads.sourceforge.net/project/postfixadmin/postfixadmin/postfixadmin-3.0.2.2/postfixadmin-3.0.2.2.tar.gz" | tar -xzf - -C /var/www/html

Open the mail configuration file and edit the following values:

nano /var/www/html/postfixadmin-3.0.2/config.inc.php

$CONF['configured'] = true;
$CONF['database_type'] = 'sqlite';
// $CONF['database_host'] = 'localhost';
// $CONF['database_user'] = 'postfix';
// $CONF['database_password'] = 'postfixadmin';
$CONF['database_name'] = '/var/vmail/postfixadmin.db';

$CONF['domain_path'] = 'NO';
$CONF['domain_in_mailbox'] = 'YES';

chown -R apache: /var/www/html/postfixadmin-3.0.2

Create the SQLite database:

touch /var/vmail/postfixadmin.db
chown vmail:mail /var/vmail/postfixadmin.db
chmod 660 /var/vmail/postfixadmin.db
usermod -a -G mail apache

To populate the database go to https://Your_IP_Address/postfixadmin-3.0.2/setup.php and you should see something like below:
Testing database connection - OK - sqlite://:xxxxx@//var/vmail/postfixadmin.db
Everything seems fine... attempting to create/update database structure

Create a new admin user:

bash /var/www/html/postfixadmin-3.0.2/scripts/postfixadmin-cli admin add admin@your_domain_name.com --password strong_password22 --password2 strong_password22 --superadmin 1 --active 1

4. Install and configure postfix

Postfix version 3 is not available in the default CentOS 7 repository so we will use the GhettoForge repository:

rpm -Uhv http://mirror.ghettoforge.org/distributions/gf/gf-release-latest.gf.el7.noarch.rpm

Install postfix3 with SQLite support with the command bellow:

yum install postfix3 postfix3-sqlite --enablerepo=gf-plus

Once the installation is completed, create the following files:

nano /etc/postfix/sqlite_virtual_alias_maps.cf

dbpath = /var/vmail/postfixadmin.db
query = SELECT goto FROM alias WHERE address='%s' AND active = '1'

nano /etc/postfix/sqlite_virtual_alias_domain_maps.cf

dbpath = /var/vmail/postfixadmin.db
query = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = '%u' || '@' || alias_domain.target_domain AND alias.active = 1 AND alias_domain.active='1'

nano /etc/postfix/sqlite_virtual_alias_domain_catchall_maps.cf

dbpath = /var/vmail/postfixadmin.db
query  = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = '@' || alias_domain.target_domain AND alias.active = 1 AND alias_domain.active='1'

nano /etc/postfix/sqlite_virtual_domains_maps.cf

dbpath = /var/vmail/postfixadmin.db
query = SELECT domain FROM domain WHERE domain='%s' AND active = '1'

nano /etc/postfix/sqlite_virtual_mailbox_maps.cf

dbpath = /var/vmail/postfixadmin.db
query = SELECT maildir FROM mailbox WHERE username='%s' AND active = '1'

nano /etc/postfix/sqlite_virtual_alias_domain_mailbox_maps.cf

dbpath = /var/vmail/postfixadmin.db
query = SELECT maildir FROM mailbox,alias_domain WHERE alias_domain.alias_domain = '%d' and mailbox.username = '%u' || '@' || alias_domain.target_domain AND mailbox.active = 1 AND alias_domain.active='1'

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Edit the main.cf file:

postconf -e "myhostname = $(hostname -f)"
 
postconf -e "virtual_mailbox_domains = sqlite:/etc/postfix/sqlite_virtual_domains_maps.cf"
postconf -e "virtual_alias_maps =  sqlite:/etc/postfix/sqlite_virtual_alias_maps.cf, sqlite:/etc/postfix/sqlite_virtual_alias_domain_maps.cf, sqlite:/etc/postfix/sqlite_virtual_alias_domain_catchall_maps.cf"
postconf -e "virtual_mailbox_maps = sqlite:/etc/postfix/sqlite_virtual_mailbox_maps.cf, sqlite:/etc/postfix/sqlite_virtual_alias_domain_mailbox_maps.cf"
 
postconf -e "smtpd_tls_cert_file = /etc/pki/tls/certs/localhost.crt"
postconf -e "smtpd_tls_key_file = /etc/pki/tls/private/localhost.key"
postconf -e "smtpd_use_tls = yes"
postconf -e "smtpd_tls_auth_only = yes"
 
postconf -e "smtpd_sasl_type = dovecot"
postconf -e "smtpd_sasl_path = private/auth"
postconf -e "smtpd_sasl_auth_enable = yes"
postconf -e "smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination"
 
postconf -e "mydestination = localhost"
postconf -e "mynetworks = 127.0.0.0/8"
postconf -e "inet_protocols = ipv4"
postconf -e "inet_interfaces = all"

postconf -e "virtual_transport = lmtp:unix:private/dovecot-lmtp"

Open the master.cf file, find submission inet n and smtps inet n sections and edit as follows:

nano /etc/postfix/master.cf

submission inet n       -       n       -       -       smtpd
  -o syslog_name=postfix/submission
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_reject_unlisted_recipient=no
#  -o smtpd_client_restrictions=$mua_client_restrictions
#  -o smtpd_helo_restrictions=$mua_helo_restrictions
#  -o smtpd_sender_restrictions=$mua_sender_restrictions
#  -o smtpd_recipient_restrictions=
  -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
  -o milter_macro_daemon_name=ORIGINATING
smtps     inet  n       -       n       -       -       smtpd
  -o syslog_name=postfix/smtps
#  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_reject_unlisted_recipient=no
#  -o smtpd_client_restrictions=$mua_client_restrictions
#  -o smtpd_helo_restrictions=$mua_helo_restrictions
#  -o smtpd_sender_restrictions=$mua_sender_restrictions
#  -o smtpd_recipient_restrictions=
  -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
  -o milter_macro_daemon_name=ORIGINATING

Enable and restart the postfix service

systemctl enable postfix
systemctl restart postfix

5. Install and Configure Dovecot

Install dovecot using the command bellow:

yum install dovecot

Open the /etc/dovecot/conf.d/10-mail.conf file and change the following values:

nano /etc/dovecot/conf.d/10-mail.conf

mail_location = maildir:/var/vmail/%d/%n
mail_privileged_group = mail
mail_uid = vmail
mail_gid = mail
first_valid_uid = 150
last_valid_uid = 150

Open the /etc/dovecot/conf.d/10-auth.conf file and change the following values:

nano /etc/dovecot/conf.d/10-auth.conf

auth_mechanisms = plain login
#!include auth-system.conf.ext
!include auth-sql.conf.ext

Create a new dovecot-sql.conf.ext file:

nano /etc/dovecot/dovecot-sql.conf.ext

driver = sqlite
connect = /var/vmail/postfixadmin.db
default_pass_scheme = MD5-CRYPT
password_query = \
  SELECT username as user, password, '/var/vmail/%d/%n' as userdb_home, \
  'maildir:/var/vmail/%d/%n' as userdb_mail, 150 as userdb_uid, 8 as userdb_gid \
  FROM mailbox WHERE username = '%u' AND active = '1'
user_query = \
  SELECT '/var/vmail/%d/%n' as home, 'maildir:/var/vmail/%d/%n' as mail, \
  150 AS uid, 8 AS gid, 'dirsize:storage=' || quota AS quota \
  FROM mailbox WHERE username = '%u' AND active = '1'

In the /etc/dovecot/conf.d/10-ssl.conf file enable SSL support:

ssl = yes

Open the /etc/dovecot/conf.d/15-lda.conf file and set the postmaster_address email address.

postmaster_address = postmaster@your_domain_name.com

Open the /etc/dovecot/conf.d/10-master.conf file, find the service lmtp section and change it to:

service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    mode = 0600
    user = postfix
    group = postfix
  }
}

find the service auth section and change it to:

service auth {
  unix_listener /var/spool/postfix/private/auth {
    mode = 0666
    user = postfix
    group = postfix
  }
  unix_listener auth-userdb {
    mode = 0600
    user = vmail
    #group = vmail
  }
  user = dovecot
}

Change the service auth-worker section to the following:

service auth-worker {
  user = vmail
}

Set the permissions:

chown -R vmail:dovecot /etc/dovecot
chmod -R o-rwx /etc/dovecot

Enable and restart the dovecot service

systemctl enable dovecot 
systemctl restart dovecot 

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If everything is setup correctly now you should be able to log in to your PostfixAdmin backend by going to http://Your_IP_Address/postfixadmin-3.0.2.2 and create your first virtual domain and mailbox.

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Of course, you don’t have to set up a mail server with PostfixAdmin on CentOS 7, if you use one of our Mail Server Hosting services, in which case you can simply ask our expert Linux admins to setup this for you. They are available 24×7 and will take care of your request immediately.

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