Linux Mail Server Setup with Postfix, Dovecot and Bind9

This repository contains a guide and configuration files for setting up a robust, self-hosted mail server on Linux systems using Postfix as the Mail Transfer Agent (MTA) and Dovecot as the IMAP/POP3 server.

Prerequisites

• A Linux server (this guide was tested on Ubuntu 24.04 LTS)
• Root access to the server
• A domain name (this guide uses a free domain from No-IP)
• Basic knowledge of Linux command line and server administration

Step-by-Step Guide

1. Update and Upgrade System

sudo apt update && sudo apt upgrade -y

2. Install required packages

sudo apt install -y postfix dovecot-core dovecot-imapd dovecot-pop3d bind9 bind9utils bind9-doc

When prompted during Postfix installation, select "Internet Site" and enter your domain name.

3. Configure Postfix

Edit the main Postfix configuration file:

sudo nano /etc/postfix/main.cf

Replace the content with the configuration provided in configs/main.cf. Make sure to replace your_domain.ddns.net with your actual domain.

4. Configure Dovecot

Edit the Dovecot configuration file:

sudo nano /etc/dovecot/dovecot.conf

Replace the content with the configuration provided in configs/dovecot.conf.

5. Configure BIND9 (if using)

Edit the BIND9 local configuration file:

sudo nano /etc/bind/named.conf.local

Add the content from configs/named.conf.local, replacing your_domain.ddns.net with your actual domain.

Create a new zone file:

sudo nano /etc/bind/db.your_domain.ddns.net

Add the content from configs/db.your_domain.ddns.net, replacing your_domain.ddns.net and your_server_ip_address with your actual domain and server IP.

6. Set Up No-IP Dynamic DNS Client

Install build tools:

sudo apt install -y build-essential

Download and install No-IP DUC:

cd /usr/local/src/
sudo wget http://www.no-ip.com/client/linux/noip-duc-linux.tar.gz
sudo tar xzf noip-duc-linux.tar.gz
cd noip-2.1.9-1/
sudo make
sudo make install

Configure No-IP DUC:

sudo /usr/local/bin/noip2 -C

Follow the prompts to enter your No-IP account details and configure the client.

7. Configure Gmail as a Relay (optional)

If you want to use Gmail as a relay for outgoing emails:

Create a file for Gmail credentials:

sudo nano /etc/postfix/sasl_passwd

Add the line from configs/sasl_passwd, replacing with your actual Gmail address and app password.

Secure the file and create the hash database:

sudo chmod 600 /etc/postfix/sasl_passwd
sudo postmap /etc/postfix/sasl_passwd

8. Restart Services

sudo systemctl restart postfix dovecot bind9
sudo /usr/local/bin/noip2

9. Test the Setup

Install mailutils:

sudo apt install -y mailutils

Send a test email:

echo "This is a test email from your new mail server." | mail -s "Test Email" your_email@example.com

Security Considerations

• Keep your system and all installed packages up to date
• Use strong passwords for all accounts
• Consider implementing SPF, DKIM, and DMARC for better email authentication
• Set up a firewall (e.g., UFW) and only allow necessary ports
• Regularly monitor your server logs for any suspicious activity

Troubleshooting

• Check /var/log/mail.log for any error messages related to Postfix or Dovecot
• Ensure all configuration files have the correct permissions
• Verify that your domain's DNS records are set up correctly
• If emails are not being sent, check if your ISP is blocking outgoing SMTP traffic

Maintenance

• Regularly update your system and installed packages
• Monitor disk usage, especially in mail directories
• Backup your configuration files and email data regularly
• Keep your No-IP dynamic DNS client running and up to date