How to Install and Configure an Email Server on Ubuntu 24.04

In this guide, we will demonstrate how to install and configure a mail server on Ubuntu 24.04, as large and medium-sized companies can greatly benefit from having a private email server. By utilizing a mail server, it becomes feasible to monitor all email traffic closely. Additionally, the flexibility to customize settings enables the establishment of a clear and organized email service. While there are various options available for setting up a Linux email server, we will specifically concentrate on Postfix and Dovecot.

Prerequisites for an Email Server on Ubuntu 24.04

• An Ubuntu 24.04 VPS
• SSH root access or a user with sudo privileges is required

Conventions

# – given commands should be executed with root privileges either directly as a root user or by use of sudo command
$ – given commands should be executed as a regular user

Step 1. Set Hostname

Hostname is a label used to identify a machine and will help you distinguish your servers from the others. You would need to create a DNS A record for your hostname because the server hostname should be an FQDN (Fully Qualified Domain Name). For example, we will use ubuntu.yourdomain.com as the server hostname in this tutorial. Subsequently, execute the following command:

$ sudo hostnamectl set-hostname ubuntu.yourdomain.com

Make sure to replace ubuntu.yourdomain.com with your own subdomain pointing to your server’s IP address

Step 2. Install Dependencies

In this step, we will install an Apache web server, PHP with its extensions, and MariaDB as the database server. Let’s execute this command below.

$ sudo apt install apache2 git mariadb-server php-{xml,pear,imap,intl,common,json,curl,mbstring,mysql,gd,imagick,zip,opcache,sqlite3} libapache2-mod-php

Step 3. Create a System User

In this step, we will create a new system user to store the emails on the server. Let’s invoke the command below.

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

Step 4. Create a Database

Next, let’s create a database. By default, you can log in to MySQL shell without a password.

$ sudo mysql

Once logged in, let’s run these commands.

MariaDB [(none)]> CREATE DATABASE postfixadmin;
MariaDB [(none)]> GRANT ALL PRIVILEGES ON postfixadmin.* TO 'postfixadmin'@'localhost' IDENTIFIED BY 'M0d1fyth15';
MariaDB [(none)]> FLUSH PRIVILEGES;
MariaDB [(none)]> \q

Step 5. Install Postfix

Install the Postfix mail server from the Ubuntu default repository with this command:

$ sudo apt install postfix-mysql

The mail server related data will be stored in a MySQL database. Once the package postfix-mysql installation is completed we need to create several configuration files for Postfix to communicate with the database.

$ sudo mkdir -p /etc/postfix/sql

Match the password, database name, and database user with those you created in the earlier step.

$ sudo nano /etc/postfix/sql/mysql_virtual_alias_maps.cf

user = postfixadmin
password = M0d1fyth15
hosts = localhost
dbname = postfixadmin
query = SELECT goto FROM alias WHERE address='%s' AND active = '1'

$ sudo nano /etc/postfix/sql/mysql_virtual_domains_maps.cf

user = postfixadmin
password = M0d1fyth15
hosts = localhost
dbname = postfixadmin
query = SELECT domain FROM domain WHERE domain='%s' AND active = '1'

$ sudo nano /etc/postfix/sql/mysql_virtual_mailbox_maps.cf

user = postfixadmin
password = M0d1fyth15
hosts = localhost
dbname = postfixadmin
query = SELECT maildir FROM mailbox WHERE username='%s' AND active = '1'

$ sudo nano /etc/postfix/sql/mysql_virtual_alias_domain_maps.cf

user = postfixadmin
password = M0d1fyth15
hosts = localhost
dbname = postfixadmin
query = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('%u', '@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

$ sudo nano /etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf

user = postfixadmin
password = M0d1fyth15
hosts = localhost
dbname = postfixadmin
query = SELECT maildir FROM mailbox,alias_domain WHERE alias_domain.alias_domain = '%d' and mailbox.username = CONCAT('%u', '@', alias_domain.target_domain) AND mailbox.active = 1 AND alias_domain.active='1'

$ sudo nano /etc/postfix/sql/mysql_virtual_mailbox_limit_maps.cf

user = postfixadmin
password = M0d1fyth15
hosts = localhost
dbname = postfixadmin
query = SELECT quota FROM mailbox WHERE username='%s' AND active = '1'

$ sudo nano /etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf

user = postfixadmin
password = M0d1fyth15
hosts = localhost
dbname = postfixadmin
query = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

Now, we can run the commands below to edit postfix’s main.cf file.

$ sudo postconf -e "myhostname = $(hostname -f)"
$ sudo postconf -e "mydestination = localhost"
$ sudo postconf -e "mynetworks = 127.0.0.0/8"
$ sudo postconf -e "inet_protocols = ipv4"
$ sudo postconf -e "inet_interfaces = all"
$ sudo postconf -e "smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem"
$ sudo postconf -e "smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key"
$ sudo postconf -e "smtpd_use_tls = yes"
$ sudo postconf -e "smtpd_tls_auth_only = yes"
$ sudo postconf -e "smtpd_sasl_type = dovecot"
$ sudo postconf -e "smtpd_sasl_path = private/auth"
$ sudo postconf -e "smtpd_sasl_auth_enable = yes"
$ sudo postconf -e "smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination"
$ sudo postconf -e "virtual_transport = lmtp:unix:private/lmtp"
$ sudo postconf -e "virtual_mailbox_domains = proxy:mysql:/etc/postfix/sql/mysql_virtual_domains_maps.cf"
$ sudo postconf -e "virtual_alias_maps = proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_maps.cf, proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_maps.cf, proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf"
$ sudo postconf -e "virtual_mailbox_maps = proxy:mysql:/etc/postfix/sql/mysql_virtual_mailbox_maps.cf, proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf"

Once completed, we can continue and edit /etc/postfix/master.cf file:

$ sudo nano /etc/postfix/master.cf

Modify or add the following lines to the file.

smtp      inet  n       -       y       -       -       smtpd
#smtp      inet  n       -       y       -       1       postscreen
#smtpd     pass  -       -       y       -       -       smtpd
#dnsblog   unix  -       -       y       -       0       dnsblog
#tlsproxy  unix  -       -       y       -       0       tlsproxy
# Choose one: enable submission for loopback clients only, or for any client.
#127.0.0.1:submission inet n -   y       -       -       smtpd
submission inet n       -       y       -       -       smtpd
  -o syslog_name=postfix/submission
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_tls_auth_only=yes
#  -o local_header_rewrite_clients=static:all
#  -o smtpd_reject_unlisted_recipient=no
#     Instead of specifying complex smtpd_<xxx>_restrictions here,
#     specify "smtpd_<xxx>_restrictions=$mua_<xxx>_restrictions"
#     here, and specify mua_<xxx>_restrictions in main.cf (where
#     "<xxx>" is "client", "helo", "sender", "relay", or "recipient").
#  -o smtpd_client_restrictions=
#  -o smtpd_helo_restrictions=
#  -o smtpd_sender_restrictions=
#  -o smtpd_relay_restrictions=
#  -o smtpd_recipient_restrictions=permit_sasl_authenticated,reject
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
  -o milter_macro_daemon_name=ORIGINATING

Step 6. Install Dovecot

Run this command to install Dovecot.

$ sudo apt install dovecot-mysql dovecot-imapd dovecot-pop3d

Once Dovecot is installed, we can proceed with the following steps and edit some configuration files.

Open the /etc/dovecot/conf.d/10-auth.conf file

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

Then, find this line

auth_mechanisms = plain

and replace the line with this one:

auth_mechanisms = plain login

Then, we need to comment !include auth-system.conf.ext and uncomment the line !include auth-sql.conf.ext

It should look like this:

#!include auth-system.conf.ext
!include auth-sql.conf.ext

Still in the 10-auth.conf file, we include auth-sql.conf.ext. So, let’s edit the file so it gets executed.

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

Insert the following lines into the file:

driver = mysql
connect = host=localhost dbname=postfixadmin user=postfixadmin password=M0d1fyth15
default_pass_scheme = BLF-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/%u' as home, 'maildir:/var/vmail/%d/%u' as mail, 150 AS uid, 8 AS gid, concat('dirsize:storage=', quota) AS quota FROM mailbox WHERE username = '%u' AND active = '1'

The lines above contain the database credentials. Make sure they match the ones you created in the previous step. Save the file and exit

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

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

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

Save the file, then exit. Now, let’s proceed with editing other dovecot configuration files.

$ sudo nano /etc/dovecot/conf.d/10-master.conf

There are several changes you need to make in this file.

Find the service lmtp section and change it to the following:

service lmtp {
    unix_listener /var/spool/postfix/private/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

}
user = dovecot
}

Change the service auth-worker section to the following:

service auth-worker {
user = vmail
}

Do not forget to save the file and then exit. And now, it is time to correct the permissions.

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

Step 7. Install PostfixAdmin

In this step, we will download PostfixAdmin from Github and store it in the /opt directory.

$ sudo cd /opt
$ sudo git clone https://github.com/postfixadmin/postfixadmin.git
$ sudo cd /opt/postfixadmin
$ sudo bash install.sh

Let’s correct the permission.

$ sudo chown -R www-data: /opt/postfixadmin

Add /etc/apache2/conf-enabled/postfixadmin.conf

$ sudo nano /etc/apache2/conf-enabled/postfixadmin.conf

Insert these lines into that file.

Alias /postfixadmin /opt/postfixadmin/public

<Directory "/opt/postfixadmin/public">
        AllowOverride All
        Options +FollowSymLinks
        Require all granted
</Directory>

Then, we need to reload Apache.

$ sudo systemctl reload apache2

Next, let’s create config.local.php

$ sudo nano /opt/postfixadmin/config.local.php

and insert the following lines

<?php
$CONF['database_type'] = 'mysqli';
$CONF['database_host'] = 'localhost';
$CONF['database_user'] = 'postfixadmin';
$CONF['database_password'] = 'M0d1fyth15';
$CONF['database_name'] = 'postfixadmin';
$CONF['configured'] = true;

?>

Save the file, then exit from the editor.

Go to http://YOUR_IP_ADDRESS/postfixadmin/setup.php and create a setup password. If you already have a website on your server, you can also access postfixadmin at http://yourdomain.com/postfixadmin/setup.php

Type your setup password twice and click on Generate setup_password hash button.

You will see a line containing a setup password, and you need to copy it to config.local.php, something like:

$CONF['setup_password'] = '$2y$10$YpUXiIQAP47pudUDz0n3leljN2ap5xBq/O1ntFmgAtU0WArEXy84y';

After adding the line to config.local.php file, you can refresh the page to log in and create a superadmin.

Scroll down to create a superadmin account. The setup password you created earlier is required to create a superadmin. In the admin field, it should be filled with an email address, it should look like this:

Now that a superadmin has been created, you can use the credentials to log in to http://192.168.53.5/postfixadmin/login.php and add domains, email address, etc.

Step 8. Install Webmail

At this point, your server can send emails. To receive emails, make sure your domain’s DNS MX record points to this server. You can use your favorite email client to send emails or use a webmail instead. Let’s install Roundcube now.

$ sudo apt install roundcube

Next, let’s edit rouncube configuration file at /etc/apache2/conf-enabled/roundcube.conf

$ sudo nano /etc/apache2/conf-enabled/roundcube.conf

Uncomment this line

# Alias /roundcube /var/lib/roundcube/public_html

And it should look like this:

Alias /roundcube /var/lib/roundcube/public_html

Save the file, exit then restart apache

$ sudo systemctl restart apache2

The next step is to edit another Rouncube config file, this one at /etc/roundcube/config.inc.php

$ sudo nano /etc/roundcube/config.inc.php

Find this string:

$config['smtp_host'] = 'localhost:587';

and replace it with this one:

$config['smtp_host'] = 'tls://%n:587';

You successfully installed an Email Server on Ubuntu 24.04

You can now navigate to your http://YOUR_SERVER_IP_ADDRESS/roundcube and log in using the credentials you created in the previous step. Once logged in, you can try to send an email.

Of course, you don’t have to install and configure an email server on Ubuntu 24.04 server if you have a server with us, in which case you can simply ask our expert Linux hosting admins to set all of this up for you, quickly and easily. They are available 24×7 and will respond to your request immediately. Our admins will also help you with more complex mail server installation, like using OpenDKIM, SPF, and DMARC.

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