# Set up a Postfix mail server with Dovecot and Squirrelmail on Ubuntu 16.04

Learn how to set up a [email server](https://www.ionos.ca/office-solutions/email-server "Email server") on a Cloud Server running Ubuntu 16.04. This tutorial features Postfix as an SMTP server, Dovecot for POP/IMAP functionality, and Squirrelmail as a webmail program for users to check and receive email from a web browser.

The tutorial will also walk you through the process of creating and using a self-signed SSL certificate for use in securing incoming and outgoing email connections.

## Requirements

- A Cloud Server running Ubuntu 16.04.
- A valid domain name pointing to the server.

## Firewall access

You will need to set your firewall(s) to allow access to the following ports:

- SMTP: 25
- POP3: 110
- IMAP: 143
- SMTP Secure: 465
- MSA: 587
- IMAP Secure: 993
- POP3 Secure: 995

By default, the Cloud Panel Firewall denies access to all but the most commonly-used ports.

## Install Postfix

To install Postfix, first update your packages:

```none
sudo apt-get update
```

Then install Postfix:

```none
sudo apt-get install postfix
```

Postfix is installed by default on most Ubuntu 16.04 systems, so this command will most likely exit with a message that postfix is already the newest version (3.1.0-3)..

If Postfix continues with an installation, simply accept all of the defaults at each prompt to complete the process.

### Configure Postfix

After the installation is complete, run the command to configure Postfix:

```none
sudo dpkg-reconfigure postfix
```

Enter the following values at the prompts, replacing example.com with your own domain name. Use the up arrow and down arrow to move up and down to highlight answers, and Enter to select your answer.

1. Select OK to proceed.
2. Choose Internet Site.
3. System Mail Name: example.com
4. Root and postmaster mail recipient: root
5. Other destinations for mail: example.com, localhost.example.com, localhost
6. Force synchronous updates on mail queue?: No
7. Local networks: 127.0.0.0/8
8. Use procmail for local delivery?: No
9. Mailbox size limit (bytes): 0
10. Local address extension character: +
11. Internet protocols to use: all

After the initial Postfix configuration has been done, you can change Postfix settings with the command:

```none
sudo postconf -e '[new setting]'
```

---

### Tip

Set up your own professional [email server](https://www.ionos.ca/office-solutions/email-server "Professional email servers from IONOS") in the blink of an eye. You benefit from large and expandable storage space, your own domain, automatic encryption as well as calendar and office functions or email archiving. IONOS also offers the highest security standards in ISO-certified data centers.

---

## Create an SSL certificate

We will create a self-signed [SSL certificate](https://www.ionos.ca/digitalguide/websites/website-creation/ssl-certificate/ "SSl certificate") to secure incoming and outgoing email connections:

```none
sudo openssl req -x509 -nodes -newkey rsa:2048 -keyout mailserver.key -out mailserver.crt -nodes -days 365
sudo openssl req -new -x509 -extensions v3_ca -keyout cakey.pem -out cacert.pem -days 3650
```

Answer the questions at the prompts, or just hit \[Enter\] to leave an answer blank. This command will create two files: mailserver.key and mailserver.crt.

Create a folder for the SSL certificate files:

```none
sudo mkdir /etc/postfix/ssl
```

Then move the files into this folder:

```none
sudo mv mailserver.key /etc/postfix/ssl
sudo mv mailserver.crt /etc/postfix/ssl
sudo mv cakey.pem /etc/postfix/ssl
sudo mv cacert.pem /etc/postfix/ssl
```

### Set up SMTP AUTH

SMTP AUTH is a basic method of securing your mail server. We strongly recommend the use of SMTP AUTH on all mail servers.

To begin, use the following commands to configure Postfix to use SMTP AUTH:

```none
sudo postconf -e 'smtpd_sasl_local_domain ='
sudo postconf -e 'smtpd_sasl_auth_enable = yes'
sudo postconf -e 'smtpd_sasl_security_options = noanonymous'
sudo postconf -e 'broken_sasl_auth_clients = yes'
sudo postconf -e 'smtpd_recipient_restrictions =  permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination'
sudo postconf -e 'inet_interfaces = all'
sudo postconf -e 'smtp_tls_security_level = may'
sudo postconf -e 'smtpd_tls_security_level = may'
sudo postconf -e 'smtpd_tls_auth_only = no'
sudo postconf -e 'smtp_tls_note_starttls_offer = yes'
sudo postconf -e 'smtpd_tls_key_file = /etc/postfix/ssl/mailserver.key'
sudo postconf -e 'smtpd_tls_cert_file = /etc/postfix/ssl/mailserver.crt'
sudo postconf -e 'smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem'
sudo postconf -e 'smtpd_tls_loglevel = 1'
sudo postconf -e 'smtpd_tls_received_header = yes'
sudo postconf -e 'smtpd_tls_session_cache_timeout = 3600s'
sudo postconf -e 'tls_random_source = dev:/dev/urandom'
```

Replace example.com with your own domain name:

```none
sudo postconf -e 'myhostname = example.com'
```

Next, create the file /etc/postfix/sasl/smtpd.conf and open it for editing:

```none
sudo nano /etc/postfix/sasl/smtpd.conf
```

Add the following content:

```none
pwcheck_method: saslauthd
mech_list: plain login
```

After you have finished configuring Postfix, restart the Postfix daemon with the command:

```none
sudo systemctl restart postfix
```

### Install SASL

Postfix will use SASL to handle the authentication with SMTP AUTH. Now that Postfix has been configured to use SMTP AUTH, install SASL with the command:

```none
sudo apt-get install libsasl2-2 sasl2-bin libsasl2-modules
```

After the installation is done, edit /etc/default/saslauthd:

```none
sudo nano /etc/default/saslauthd
```

Scroll down to the line:

```none
# Should saslauthd run automatically on startup? (default: no)
START=no
```

Change START to yes:

```none
# Should saslauthd run automatically on startup? (default: no)
START=yes
```

Below that line, add the following three lines:

```none
PWDIR="/var/spool/postfix/var/run/saslauthd"
PARAMS="-m ${PWDIR}"
PIDFILE="${PWDIR}/saslauthd.pid"
```

Scroll down to the bottom of the file to the line:

```none
OPTIONS="-c -m /var/run/saslauthd"
```

Change the last line to read:

```none
OPTIONS="-c -m /var/spool/postfix/var/run/saslauthd"
```

Save and exit the file.

Next, run the following command to update the dpkg state:

```none
sudo dpkg-statoverride --force --update --add root sasl 755 /var/spool/postfix/var/run/saslauthd
```

Note: If you get an error message that /var/spool/postfix/var/run/saslauthd does not exist, ignore it. This directory will be created when you start the SASL daemon.

Create a symlink for the config file:

```none
sudo ln -s /etc/default/saslauthd /etc/saslauthd
```

And finally, start the SASL daemon:

```none
sudo /etc/init.d/saslauthd start
```

### Test Postfix with Telnet

To test Postfix we will telnet to the server and perform a basic "handshake protocol," just as an email program would.

First, install Telnet:

```none
sudo apt-get install telnet
```

Once Telnet is installed, use it to connect to the server's SMTP port:

```none
telnet localhost 25
```

The server will respond with:

```none
[user@localhost ~]$ telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 localhost.localdomain ESMTP Postfix (Ubuntu)
```

This indicates that Postfix is up and running.

Next, greet the server:

```none
ehlo localhost
```

The server will respond with:

```none
250-localhost.localdomain
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
```

The following lines indicate that SMTP AUTH is working:

```none
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
```

Start by telling the server who the mail is being sent from:

```none
mail from: some-person@some-other-server.com
```

Then tell the server who you are sending mail to, replacing user@example.com with your own username and domain name:

```none
rcpt to: root@example.com
```

Now add a simple message. Tell the server your message body starts here:

```none
data
```

Type the message, then follow it with \[Enter\], a period ., and \[Enter\]:

```none
hello world 
.
```

Close the session by typing quit and hitting Enter.

If you are successful, your test message will appear in /root/Maildir/new. You can view this message with the command:

```none
ll /root/Maildir/new
```

To read the message, copy and paste the name of the file (it will be a long name like 1482257384.Vfc00I60512M258205.localhost.localdomain) and read it with more:

```none
sudo more  1482257384.Vfc00I60512M258205.localhost.localdomain
```

You will see the email message, along with all of the header information:

```none
From some-person@some-other-server.com  Thu Dec  8 19:43:10 2016
Return-Path: <some-person@some-other-server.com>
X-Original-To: root@example.com
Delivered-To: root@example.com
Received: from localhost (localhost [127.0.0.1])
    by mail.example.com (Postfix) with SMTP id 6CFD589184
    for <root@example.com>; Thu,  8 Dec 2016 19:42:33 +0000 (UTC)
Message-Id: <20161208194238.6CFD589184@mail.oxnardindustries.com>
Date: Thu,  8 Dec 2016 19:42:33 +0000 (UTC)
From: some-person@some-other-server.com
hello world
```

## Install and configure Dovecot

Dovecot is the default POP3/IMAP server for Ubuntu, and is installed on most Ubuntu 16.04 servers by default. Update Dovecot and install the imapd package with the command:

```none
sudo apt-get install dovecot-core dovecot-imapd
```

You can check on the status of Dovecot with the command:

```none
sudo systemctl status dovecot
```

If Dovecot is running, you will see output similar to:

```none
[user@mail dovecot]$ sudo systemctl status dovecot -l
● dovecot.service - Dovecot IMAP/POP3 email server
   Loaded: loaded (/usr/lib/systemd/system/dovecot.service; disabled; vendor preset: disabled)
   Active: active (running) since Thu 2016-12-08 21:04:48 UTC; 3s ago
  Process: 8985 ExecStartPre=/usr/libexec/dovecot/prestartscript (code=exited, status=0/SUCCESS)
 Main PID: 8989 (dovecot)
   CGroup: /system.slice/dovecot.service
           ├─8989 /usr/sbin/dovecot -F
           ├─8992 dovecot/anvil
           ├─8993 dovecot/log
           └─8995 dovecot/config
Dec 08 21:04:48 example.com systemd[1]: Starting Dovecot IMAP/POP3 email server...
Dec 08 21:04:48 example.com systemd[1]: Started Dovecot IMAP/POP3 email server.
Dec 08 21:04:48 example.com dovecot[8989]: master: Dovecot v2.2.10 starting up for imap (core dumps disabled)
```

Note the line that reads:

```none
Active: active (running) since Thu 2016-12-08 21:04:48 UTC; 3s ago
```

This means that Dovecot is installed and running.

Set the permissions on the /var/mail directory so that Dovecot can create folders for new users:

```none
sudo chmod 777 /var/mail
```

## Install and configure Squirrelmail

Install Squirrelmail with the command:

```none
sudo apt-get install squirrelmail
```

You will need to edit your Apache configurations to add an alias for Squirrelmail. This directive will need to be inserted inside the VirtualHost command block in the site's main Apache configuration file.

By common convention, this Apache configuration file is usually /etc/apache2/sites-available/example.com.conf on Ubuntu.

Note: The location and filename of a site's Apache configuration file can vary.

Edit this file with your editor of choice, for example with the command:

```none
sudo nano /etc/apache2/sites-available/example.com.conf
```

Scroll through the file until you find the VirtualHost command block, which will look like:

```none
<VirtualHost *:80>
ServerName example.com
    <Directory "/var/www/example.com/html">
    AllowOverride All
    </Directory>
</VirtualHost>
```

Add the following to VirtualHost command block:

```none
Alias /squirrelmail /usr/share/squirrelmail
```

Be sure to put these lines outside any Directory command blocks. For example:

```none
<VirtualHost *:80>
ServerName example.com
Alias /squirrelmail /usr/share/squirrelmail
    <Directory "/var/www/example.com/html">
    AllowOverride All
    </Directory>
</VirtualHost>
```

Save and exit the file, then restart Apache for the changes to take effect:

```none
sudo systemctl restart apache2
```

After Apache restarts, you can test Squirrelmail by visiting the URL http://example.com/squirrelmail in a browser.


This is a markdown version of: [https://www.ionos.ca/digitalguide/e-mail/technical-matters/set-up-a-postfix-mail-server-with-dovecot-and-squirrelmail-on-ubuntu/](https://www.ionos.ca/digitalguide/e-mail/technical-matters/set-up-a-postfix-mail-server-with-dovecot-and-squirrelmail-on-ubuntu/) for AI/LLM consumption.