go-mailshield

Motivation

This project was created for two main reasons:

• Learning Project: As a practical project to learn and deepen my Go programming skills. Working with IMAP, containers, and concurrent programming provides an excellent opportunity to apply various aspects of Go in practice.
• Practical Problem: My email provider unfortunately doesn't offer sufficient spam filtering mechanisms. With this tool, I can use SpamAssassin as an additional filtering layer to keep my inbox clean.

What does go-mailshield do?

go-mailshield connects to your IMAP accounts, regularly checks for new emails, and forwards them to SpamAssassin for spam detection. Emails identified as spam are moved to the configured spam folder.

Features

• Monitoring of multiple IMAP accounts
• Integration with SpamAssassin for reliable spam detection
• Fully containerized solution with Docker
• Configurable check intervals
• Option to check only unread emails

Installation

Prerequisites

• Docker and Docker Compose
• Go 1.22+ (for development only)

Setup

• Clone the repository:

git clone https://github.com/yourusername/go-mailshield.git
cd go-mailshield

• Create a configuration file:

cp config.yaml.dist config.yaml

• Adjust the configuration (see Configuration section)

• Start with Docker:

docker compose up -d

Configuration

Edit the config.yaml according to your needs:

poll_interval: 30s  # Check interval
workers: 2          # Number of parallel workers
accounts:
  - name: "primary"
    host: "imap.example.com:993"
    tls: true
    username: "user@example.com"
    password: "yourpassword"
    inbox: "INBOX"
    spam_folder: "Spam"
    search_unseen_only: true

Development

For development, you can run SpamAssassin in a container and your Go app locally:

# Start only SpamAssassin
docker compose up spamassassin

# In another terminal
go run .

Technical Background

• Uses the go-imap library for IMAP communication
• SpamAssassin runs in a separate Docker container
• Implements goroutines for parallel processing
• Uses Context for clean shutdown handling

Known Issues

• Handling for the "worker" config value is missing
• Logging instead of output

License

MIT

---

This project is a personal learning project and is actively being developed.