Install RedMail with Virtual Domains, Webmail, SpamAssassin & ClamAV in Linux

Introduction

Email communication remains an integral part of our personal and professional lives. Setting up a reliable and secure mail server is crucial for efficient communication within organizations or for personal use. RedMail, a fully-featured mail server solution, offers a comprehensive suite of tools to create virtual domains, access webmail, and enhance email security with SpamAssassin and ClamAV. In this article, we will guide you through the process of installing RedMail on a Linux system, showcasing examples and their outputs to help you get started.

Prerequisites

Before we dive into the installation process, make sure you have a Linux server with root access and a domain name pointing to your server's IP address. It's also recommended to have a basic understanding of Linux system administration.

Update Your System

To begin, log in to your Linux server as the root user and update the system packages. Open the terminal and execute the following commands −

$ sudo apt update
$ sudo apt upgrade -y

Install Required Packages

RedMail requires specific packages to function properly. Install them by running the following command −

$ sudo apt install wget curl perl net-tools dnsmasq libidn2-0 libsodium23 mariadb-server mariadb-client -y

Download and Run the RedMail Installation Script

RedMail provides a convenient installation script that automates the process. Download the script and make it executable with the following commands −

$ wget https://github.com/mail-in-a-box/mailinabox/releases/download/v0.44/setup.sh
$ chmod +x setup.sh

Start the Installation

Run the installation script to begin the RedMail installation process −

$ sudo ./setup.sh

The script will prompt you for various configuration options. Follow the on-screen instructions and provide the required information, such as your domain name, administrator email address, and passwords for different services.

Configure Virtual Domains

After the installation completes, you can configure virtual domains. This allows you to host multiple email domains on a single server. To add a virtual domain, execute the following command −

$ sudo mailinabox/tools/mail.py

You will be presented with a menu. Select option 3, "Add a new mail user or alias," and follow the prompts to add a new virtual domain.

Accessing Webmail

RedMail provides a web-based interface for accessing emails. To access the webmail interface, open your preferred web browser and enter your server's IP address or domain name, followed by "/mail" in the address bar. For example − http://your-domain.com/mail.

Enhance Email Security with SpamAssassin and ClamAV

SpamAssassin and ClamAV are powerful tools for detecting and filtering spam emails and viruses. RedMail comes with preconfigured settings for these tools. However, you can customize them as per your requirements. To check the configuration or make changes, execute the following commands −

To configure SpamAssassin −

$ sudo nano /etc/spamassassin/local.cf

To configure ClamAV −

$ sudo nano /etc/clamav/clamd.conf

Make the necessary changes and save the files.

Test the Configuration

To ensure that your RedMail installation is functioning correctly, we will perform a few tests.

Test 1: Send and Receive Email

Use an email client like Thunderbird or Outlook to send an email to an address hosted on your RedMail server. Confirm that you can successfully send and receive emails.

Test 2: Spam Filtering

Send a test email containing known spam keywords or phrases to your RedMail server. Check if the email is correctly flagged as spam and moved to the spam folder.

Test 3: Virus Scanning

Send an email with an attached file containing a known virus or malware. Confirm that ClamAV detects the threat and quarantines the email.

SSL Certificate Configuration

To ensure secure communication between your mail server and clients, it's crucial to configure SSL certificates. Let's encrypt offers free SSL certificates that can be easily integrated into RedMail. Follow these steps to obtain and configure an SSL certificate −

Install Certbot

Certbot is a tool that simplifies the process of obtaining and installing SSL certificates. Install Certbot by running the following command −

$ sudo apt install certbot -y

Obtain SSL Certificate

Use Certbot to obtain an SSL certificate for your RedMail domain. Execute the following command −

$ sudo certbot certonly --standalone -d your-domain.com

Replace "your-domain.com" with your actual domain name. Certbot will automatically validate your domain ownership and issue the SSL certificate.

Configure Nginx

RedMail uses Nginx as a web server. To configure Nginx to use the SSL certificate, open the Nginx configuration file −

$ sudo nano /etc/nginx/sites-available/default

Find the following lines −

#ssl_certificate /etc/nginx/ssl/mail.crt;
#ssl_certificate_key /etc/nginx/ssl/mail.key;

Uncomment these lines by removing the '#' at the beginning. Then, update the paths to point to your SSL certificate and private key files. Save the file and exit.

Restart Nginx

After configuring Nginx, restart the service to apply the changes −

$ sudo systemctl restart nginx

Test SSL Configuration

To ensure the SSL certificate is configured correctly, access your RedMail web interface using the HTTPS protocol (https://your-domain.com/mail). You should see a secure connection with a valid SSL certificate.

DKIM Configuration

DomainKeys Identified Mail (DKIM) is a method of email authentication that helps prevent email spoofing. RedMail supports DKIM, and configuring it enhances the trustworthiness of your outgoing emails. Follow these steps to set up DKIM −

Generate DKIM Keys

Run the following command to generate DKIM keys −

$ sudo amavisd-new genrsa /etc/dkim/your-domain.com.pem
$ sudo amavisd-new dkim_key_import -d your-domain.com -s default -k /etc/dkim/your-domain.com.pem

Replace "your-domain.com" with your actual domain name.

Configure Amavis

Open the Amavis configuration file using the following command −

$ sudo nano /etc/amavis/conf.d/50-user

Find the following line −

# @dkim_signature_options_bysender_maps = ( { '.' => { ttl => 21*24*3600, c => 'relaxed/relaxed' } } );

Uncomment this line by removing the '#', and save the file.

Restart Services

Restart the Amavis and Postfix services to apply the changes −

$ sudo systemctl restart amavis
$ sudo systemctl restart postfix

Conclusion

Setting up a fully-featured mail server like RedMail with virtual domains, webmail, and advanced security features is essential for efficient email communication. In this article, we guided you through the installation process, including the necessary configuration steps and testing procedures. By following these steps, you can create a robust and secure email infrastructure tailored to your needs. Remember to regularly update your server and security configurations to stay protected from emerging threats.