🐳 Docker Mail Server Lab (DNS + Postfix + Dovecot)

This project deploys a complete email server infrastructure using Docker containers. It simulates a real-world production environment by separating services into distinct containers (DNS, MTA, MDA), interconnected via a private network and shared volumes for data persistence.

🏗 Project Architecture

The system consists of 3 main services communicating within the isrv-net network (Subnet: 192.168.57.0/24).

Service	Hostname	Fixed IP	Role
BIND9	ns.isrv.test	192.168.57.10	Authoritative DNS server and name resolution.
Postfix	postfix.isrv.test	192.168.57.11	MTA (Mail Transfer Agent). Receives emails via SMTP.
Dovecot	dovecot.isrv.test	192.168.57.12	MDA (Mail Delivery Agent). Serves emails via IMAP/POP3.

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Data Flow Diagram

graph TD
    Client[Thunderbird Client] -->|DNS Query| DNS(Bind9 .10)
    Client -->|SMTP Port 25| Postfix(Postfix .11)
    Client -->|IMAP Port 143| Dovecot(Dovecot .12)
    
    Postfix -- Saves mail to --> Vol[(Shared Volume /home)]
    Dovecot -- Reads mail from --> Vol[(Shared Volume /home)]

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🚀 Quick Deployment

Prerequisites

• Docker and Docker Compose installed.

Installation

1. Clone the repository:

   git clone https://github.com/CrIsTiAnPvP/Mail-Server
   cd Mail-Server

2. Start the environment:

   You can use the pre-built images or build locally:

   docker compose up -d

3. Configure Host DNS:

   For your computer to resolve the isrv.test domain, add the DNS container IP to your network configuration.

   • Linux: Edit /etc/resolv.conf and add nameserver 192.168.57.10 at the top.
   • Windows: Change the IPv4 DNS settings of your network adapter to 192.168.57.10.

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⚙️ Mail Client Configuration

To connect using Thunderbird, Outlook, or any other client, use the following parameters.

User Credentials (Pre-created)

Users are automatically generated in the Dockerfile with synchronized UIDs (1001 and 1002) to ensure read/write permissions on the shared volume.

Username	Password
pepe	password
maria	password

Connection Parameters

Protocol	Server	Port	SSL/TLS	Authentication
IMAP (Incoming)	imap.isrv.test	143	None	Normal Password
SMTP (Outgoing)	smtp.isrv.test	25	None	Normal Password
POP3 (Optional)	pop.isrv.test	110	None	Normal Password

Note: Since this is a lab environment, SSL/TLS is disabled (ssl = no). You will need to accept security warnings in Thunderbird.

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🛠 Technical Details

1. DNS (Bind9)

Zone configured: isrv.test

• MX Record: Points to postfix.isrv.test (Priority 10).
• CNAMEs: smtp, imap, pop configured for ease of use.

2. Postfix (SMTP)

• Mailbox: Uses Maildir/ format (not mbox).
• Trusted Networks: 192.168.57.0/24 and 10.112.0.0/16.
• Volume: Mounts mail-data to /home for persistence.

3. Dovecot (IMAP/POP3)

• Reading: Looks for emails in ~/Maildir.
• Auth: plaintext authentication enabled for testing purposes.
• Volume: Shares the same volume as Postfix to read delivered emails.

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🔄 CI/CD (GitHub Actions)

This repository features an automated workflow located at .github/workflows/publish.yml.

• Trigger: Pushes to the main branch and changes within the Dockerfiles/ directory.
• Optimization: Uses a Matrix Strategy combined with Path Filtering. It only rebuilds and pushes the image of the specific service that changed (DNS, Dovecot, or Postfix), saving compute time.
• Registries: Automatically publishes images to:
  • Docker Hub
  • GitHub Container Registry (GHCR)

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📂 Project Structure

├── .github/
│   └── workflows/           # CI/CD Pipeline configuration
├── Dockerfiles/
│   ├── dns/                 # BIND9 Configuration
│   │   ├── db.isrv.test     # Forward Lookup Zone
│   │   ├── named.conf.local # Local configuration
│   │   ├── named.conf.options # BIND9 options
│   │   └── Dockerfile
│   ├── postfix/             # MTA Configuration
│   │   ├── main.cf
│   │   └── Dockerfile
│   └── dovecot/             # IMAP/POP3 Configuration
│       ├── conf.d/          # 10-mail, 10-auth, etc.
│       └── Dockerfile
├── docker-compose.yml       # Orchestration of the 3 services
├── LICENSE                  # License file
└── README.md