How to Host Your Own Email Server Linux: A Beginner’s Guide for Dev

Dear Dev, if you’re looking for an alternative to mainstream email services providers such as Gmail, Yahoo, or Outlook, hosting your own email server might be the solution for you. By doing so, you’ll have complete control over your email data, privacy, and security. In this article, we’ll guide you through the process of setting up your own email server on Linux step-by-step. We assume that you have some basic knowledge of Linux, networking, and system administration. Let’s get started!

Part 1: Understanding the Basics

Before we dive into the technical details, let’s clarify some basic concepts related to email servers:

What is an Email Server?

An email server is a software program that runs on a computer and allows users to send and receive emails. It works by routing messages between different email clients (such as Thunderbird or Outlook) and other email servers on the Internet. In order to set up your own email server, you’ll need a dedicated computer or virtual machine that’s always connected to the Internet and running a Linux operating system.

Why Host Your Own Email Server?

Hosting your own email server has several advantages:

• Privacy and control: You’ll have complete control over your email data and privacy. You won’t have to rely on third-party providers, who might scan your emails for advertising or marketing purposes.
• Security: You’ll be able to implement your own security measures, such as encryption, firewalls, and spam filters.
• Customization: You’ll be able to customize your email server according to your needs and preferences, such as adding new features, integrating with other services, or creating custom email addresses.
• Cost: Hosting your own email server can be cheaper in the long run, especially if you have a large number of users or need advanced features that are not available in mainstream providers.

Types of Email Servers

There are two main types of email servers: POP (Post Office Protocol) and IMAP (Internet Message Access Protocol). POP is an older protocol that downloads emails from the server to the client, while IMAP allows users to access and manipulate emails directly on the server. We’ll be using IMAP in this guide.

Part 2: Installing the Required Software

Before we can set up our email server, we need to install some software packages:

1. Install Ubuntu Server

We’ll be using Ubuntu Server as our Linux distribution. You can download the latest version from the official website (https://ubuntu.com/download/server). Follow the installation instructions to create a bootable USB drive and install Ubuntu on your dedicated computer or virtual machine. Make sure to install the OpenSSH server during the installation process, as we’ll be using it later to remotely access our server.

2. Install Postfix

Postfix is a popular mail transfer agent (MTA) that we’ll be using to handle incoming and outgoing emails. You can install it by running the following command:

sudo apt-get updatesudo apt-get install postfix

During the installation process, you’ll be asked to configure some basic settings for Postfix, such as the type of email server you want to set up (Internet Site), the server name, and the root email address. You can leave the default options for now, as we’ll configure them later.

3. Install Dovecot

Dovecot is an open-source IMAP and POP3 server that we’ll be using to provide email access to our users. You can install it by running the following command:

sudo apt-get install dovecot-core dovecot-imapd dovecot-lmtpd

During the installation process, you’ll be asked to configure some basic settings for Dovecot, such as the protocols you want to enable (IMAP and LMTP), the SSL certificate, and the authentication method. Again, you can leave the default options for now, as we’ll configure them later.

Part 3: Configuring the Email Server

Now that we have installed the required software packages, we can start configuring our email server. This involves several steps:

1. Configuring Postfix

Postfix has a main configuration file located at /etc/postfix/main.cf. You can edit it by running the following command:

sudo nano /etc/postfix/main.cf

Here are some important settings that you need to configure:

Setting	Description
myhostname	The fully qualified domain name (FQDN) of your email server, such as mail.yourdomain.com.
myorigin	The domain name that will appear in the From header of outgoing emails, such as yourdomain.com.
mydestination	The domains that your email server will accept emails for, such as yourdomain.com and localhost.
mynetworks	The IP addresses or networks that are allowed to send emails through your email server, such as 192.168.0.0/24.
smtpd_tls_cert_file	The path to your SSL certificate file.
smtpd_tls_key_file	The path to your SSL private key file.
smtpd_use_tls	Whether to use TLS encryption for incoming emails.
smtp_tls_security_level	The minimum TLS encryption level for outgoing emails.
smtpd_sasl_type	The authentication method for incoming emails, such as dovecot.
smtpd_sasl_path	The path to the authentication socket for incoming emails.

After you have made your changes, save the file and restart Postfix by running the following command:

sudo systemctl restart postfix

2. Configuring Dovecot

Dovecot has a main configuration file located at /etc/dovecot/dovecot.conf. You can edit it by running the following command:

sudo nano /etc/dovecot/dovecot.conf

Here are some important settings that you need to configure:

Setting	Description
protocols	The protocols that Dovecot will enable, such as imap and lmtp.
ssl_cert	The path to your SSL certificate file.
ssl_key	The path to your SSL private key file.
auth_mechanisms	The authentication methods that Dovecot will use, such as plain and login.
auth_socket_path	The path to the authentication socket for Postfix.
mail_location	The directory where Dovecot will store the email messages, such as maildir:/var/mail/vhosts/%d/%n.
mail_privileged_group	The group that has read and write access to the mail_location directory, such as mail.
first_valid_uid	The UID of the user that owns the mail_location directory, such as 5000.
first_valid_gid	The GID of the mail_privileged_group, such as 5000.

After you have made your changes, save the file and restart Dovecot by running the following command:

sudo systemctl restart dovecot

3. Configuring User Accounts

Now that we have configured our email server software, we need to create user accounts for our email clients. You can create a new user by running the following command:

sudo useradd -m -s /bin/bash username

Replace “username” with the desired username for your user. This will create a new home directory for the user at /home/username.

Next, you need to set a password for the user by running the following command:

sudo passwd username

Enter a strong password for your user and remember it, as you’ll need it to configure your email client later.

Part 4: Testing the Email Server

Now that we have configured our email server, we can test it by sending and receiving some emails.

1. Sending Test Emails

You can send a test email by running the following command:

echo "Test Email" | mail -s "Test Subject" user@yourdomain.com

Replace “user@yourdomain.com” with the email address of your user. This will send an email with the subject “Test Subject” and the body “Test Email” to your user.

2. Receiving Test Emails

You can receive a test email by configuring your email client to connect to your email server using the IMAP protocol. Here are the settings that you need to use:

• Username: youruser@yourdomain.com
• Password: the password that you set for your user
• Incoming server: mail.yourdomain.com
• Encryption: SSL/TLS
• Port: 993

After you have configured your email client, you should be able to see the test email that you sent earlier.

Part 5: Troubleshooting and Frequently Asked Questions

In this section, we’ll address some common issues and questions related to hosting your own email server on Linux:

1. How Do I Fix “Relay Access Denied” Error?

If you’re getting a “Relay Access Denied” error when trying to send emails from your email client, it means that Postfix is not configured to allow relay access for your IP address or network. To fix this, you need to edit the /etc/postfix/main.cf file and add your IP address or network to the mynetworks setting. For example:

mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 192.168.0.0/24

This will allow the IP address range 192.168.0.0/24 to relay emails through your email server.

2. How Do I Add Multiple Domains?

If you want to add multiple domains to your email server, you need to configure Postfix and Dovecot accordingly. Here are the steps:

• Edit the /etc/postfix/main.cf file and add the additional domains to the mydestination setting, separated by commas. For example: mydestination = localhost, yourdomain.com, yourotherdomain.com
• Create a new directory for each domain under the mail_location directory, such as /var/mail/vhosts/yourotherdomain.com. Make sure to set the correct permissions and ownership for each directory.
• Edit the /etc/dovecot/dovecot.conf file and add a new mail_location setting for each domain, such as maildir:/var/mail/vhosts/%d/%n for the default domain and maildir:/var/mail/vhosts/yourotherdomain.com/%n for the other domain.
• Restart Postfix and Dovecot to apply the changes.

3. How Do I Set Up Spam Filtering?

If you’re getting a lot of spam emails, you can set up spam filtering to automatically move them to a spam folder or delete them. There are several spam filtering software packages available for Linux, such as SpamAssassin and Amavisd-new. You can install them by running the following command:

sudo apt-get install spamassassin amavisd-new

After you have installed the software, you need to configure Postfix and Dovecot to use them. Here are the steps:

• Edit the /etc/postfix/main.cf file and add the following settings:

smtpd_recipient_restrictions = check_policy_service inet:127.0.0.1:10023content_filter = amavis:[127.0.0.1]:10024receive_override_options = no_address_mappings

• Edit the /etc/dovecot/dovecot.conf file and add the following setting:

protocol lmtp {mail_plugins = $mail_plugins sievepostmaster_address = postmaster@yourdomain.comhostname = mail.yourdomain.comlog_path = /var/log/dovecot/lmtp.loginfo_log_path = /var/log/dovecot/lmtp-info.logauth_socket_path = /var/run/dovecot/auth-mastermail_plugins = $mail_plugins sievesieve_before = /var/vmail/%d/%n/.dovecot.sievesieve = /var/vmail/%d/%n/sieve/script.sievesieve_dir = /var/vmail/%d/%n/sievesieve_global_dir = /var/vmail/sieve/}

4. How Do I Configure SSL Certificate?

If you want to use SSL encryption for your email traffic, you need to configure an SSL certificate for your domain. You can either use a free Let’s Encrypt certificate or purchase a commercial one. Here are the steps to configure a Let’s Encrypt certificate:

• Install Certbot by running the following command:

sudo apt-get updatesudo apt-get install certbot python3-certbot-nginx

• Obtain a new SSL certificate by running the following command:

sudo certbot certonly --standalone --agree-tos --no-eff-email --email your-email-address -d mail.yourdomain.com

Replace “your-email-address” with your email address and “mail.yourdomain.com” with your email server FQDN. This will obtain a new SSL certificate and store it in /etc/letsencrypt/live/mail.yourdomain.com.

• Edit the /etc/postfix/main.cf file and add the following settings:

smtpd_tls_cert_file = /etc/letsencrypt/live/mail.yourdomain.com/fullchain.pemsmtpd_tls_key_file = /etc/letsencrypt/live/mail.yourdomain.com/privkey.pemsmtpd_use_tls = yes

• Edit the /etc/dovecot/dovecot.conf file and add the following settings:

ssl_cert = /etc/letsencrypt/live/mail.yourdomain.com/fullchain.pemssl_key = /etc/letsencrypt/live/mail.yourdomain.com/privkey.pem

After you have made your changes, save the files and restart Postfix