Merge pull request #1 from christianlouis/copilot/create-pop3-to-gmail-docker

Implement self-hosted POP3 to Gmail forwarder with Docker deployment
This commit is contained in:
Christian Krakau-Louis
2026-02-01 13:27:38 +01:00
committed by GitHub
13 changed files with 1638 additions and 2 deletions
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# Python cache
__pycache__/
*.py[cod]
# Virtual environment
venv/
env/
# Environment files
.env
.env.local
# Logs
*.log
logs/
# IDE
.vscode/
.idea/
*.swp
# OS files
.DS_Store
Thumbs.db
# Git
.git/
.gitignore
# Documentation temporary files
*.tmp
# Testing
.pytest_cache/
.coverage
# Build artifacts
dist/
build/
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# POP3 Configuration (supports multiple accounts)
# Format: POP3_ACCOUNT_N where N is 1,2,3...
POP3_ACCOUNT_1_HOST=pop.example.com
POP3_ACCOUNT_1_PORT=995
POP3_ACCOUNT_1_USER=user@example.com
POP3_ACCOUNT_1_PASSWORD=your_password
POP3_ACCOUNT_1_USE_SSL=true
# Add more accounts as needed
# POP3_ACCOUNT_2_HOST=pop.another.com
# POP3_ACCOUNT_2_PORT=995
# POP3_ACCOUNT_2_USER=user@another.com
# POP3_ACCOUNT_2_PASSWORD=another_password
# POP3_ACCOUNT_2_USE_SSL=true
# Gmail/SMTP Configuration
SMTP_HOST=smtp.gmail.com
SMTP_PORT=587
SMTP_USER=your-email@gmail.com
SMTP_PASSWORD=your-app-password
SMTP_USE_TLS=true
# Gmail destination
GMAIL_DESTINATION=your-email@gmail.com
# Postmarkapp for Error Notifications
POSTMARK_API_TOKEN=your-postmark-api-token
POSTMARK_FROM_EMAIL=errors@yourdomain.com
POSTMARK_TO_EMAIL=admin@yourdomain.com
# Scheduling
CHECK_INTERVAL_MINUTES=5
MAX_EMAILS_PER_RUN=50
# Throttling (emails per minute)
THROTTLE_EMAILS_PER_MINUTE=10
# Logging
LOG_LEVEL=INFO
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# Python
__pycache__/
*.py[cod]
*$py.class
*.so
.Python
build/
develop-eggs/
dist/
downloads/
eggs/
.eggs/
lib/
lib64/
parts/
sdist/
var/
wheels/
*.egg-info/
.installed.cfg
*.egg
# Virtual Environment
venv/
ENV/
env/
# Environment variables
.env
.env.local
# IDE
.vscode/
.idea/
*.swp
*.swo
*~
# Logs
*.log
logs/
# OS
.DS_Store
Thumbs.db
# Testing
.pytest_cache/
.coverage
htmlcov/
# Temporary files
/tmp/
*.tmp
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# Contributing to POP3 to Gmail Forwarder
Thank you for your interest in contributing! This document provides guidelines for contributing to the project.
## Code of Conduct
Be respectful and inclusive. We welcome contributions from everyone.
## How to Contribute
### Reporting Bugs
1. Check if the bug has already been reported in [Issues](https://github.com/christianlouis/pop_puller_to_gmail/issues)
2. If not, create a new issue with:
- Clear title and description
- Steps to reproduce
- Expected vs actual behavior
- Environment details (OS, Docker version, etc.)
- Relevant logs (remove sensitive info!)
### Suggesting Features
1. Check the [Roadmap](ROADMAP.md) to see if it's already planned
2. Open an issue with the "enhancement" label
3. Describe the feature and its use case
4. Explain why it would be useful
### Pull Requests
1. **Fork the repository**
2. **Create a feature branch**
```bash
git checkout -b feature/your-feature-name
```
3. **Make your changes**
- Follow existing code style
- Add comments for complex logic
- Update documentation if needed
4. **Test your changes**
```bash
# Test Python syntax
python3 -m py_compile pop3_forwarder.py
# Test Docker build
docker build -t pop3-test .
# Test with your configuration
docker-compose up
```
5. **Commit your changes**
```bash
git commit -m "Add feature: brief description"
```
Use clear, descriptive commit messages:
- `Add feature: ...`
- `Fix bug: ...`
- `Update docs: ...`
- `Improve performance: ...`
6. **Push to your fork**
```bash
git push origin feature/your-feature-name
```
7. **Open a Pull Request**
- Describe what changes you made
- Reference any related issues
- Include screenshots for UI changes
## Development Setup
### Local Development
```bash
# Clone your fork
git clone https://github.com/YOUR-USERNAME/pop_puller_to_gmail.git
cd pop_puller_to_gmail
# Create virtual environment
python3 -m venv venv
source venv/bin/activate # On Windows: venv\Scripts\activate
# Install dependencies
pip install -r requirements.txt
# Copy example config
cp .env.example .env
# Edit .env with test credentials
# Run locally
python pop3_forwarder.py
```
### Docker Development
```bash
# Build image
docker build -t pop3-dev .
# Run with your config
docker run --env-file .env pop3-dev
```
## Code Style
- Follow PEP 8 for Python code
- Use meaningful variable and function names
- Add docstrings to functions and classes
- Keep functions focused and small
- Handle errors gracefully
## Testing
Before submitting a PR:
1. **Syntax check**
```bash
python3 -m py_compile pop3_forwarder.py
```
2. **Docker build**
```bash
docker build -t pop3-test .
```
3. **Manual testing**
- Test with real POP3 account (or mock)
- Verify emails are forwarded correctly
- Check error handling
- Review logs
## Documentation
Update documentation when:
- Adding new features
- Changing configuration options
- Modifying behavior
- Adding dependencies
Files to update:
- `README.md` - Main documentation
- `QUICKSTART.md` - If setup changes
- `MVP.md` - If MVP scope changes
- `ROADMAP.md` - If adding future plans
## Security
- **Never commit credentials** or sensitive data
- Use environment variables for secrets
- Report security issues privately (see below)
- Follow security best practices
### Reporting Security Issues
**Do NOT open public issues for security vulnerabilities.**
Email security concerns to the maintainers privately.
## Questions?
- Open a discussion in GitHub Discussions
- Comment on relevant issues
- Ask in pull requests
## Recognition
Contributors will be recognized in:
- GitHub contributors list
- Release notes for significant contributions
- README acknowledgments section
Thank you for contributing! 🎉
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FROM python:3.11-slim
# Set working directory
WORKDIR /app
# Install dependencies
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
# Copy application code
COPY pop3_forwarder.py .
# Create non-root user for security
RUN useradd -m -u 1000 forwarder && \
chown -R forwarder:forwarder /app
USER forwarder
# Run the application
CMD ["python", "-u", "pop3_forwarder.py"]
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MIT License
Copyright (c) 2026 POP3 to Gmail Forwarder Contributors
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
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# MVP (Minimum Viable Product) Plan
## Overview
The MVP provides core functionality to replace Gmail's POP3 import feature with a self-hosted Docker solution.
## MVP Scope
### ✅ Completed Core Features
1. **POP3 Email Fetching**
- Connect to POP3 mailboxes using SSL/TLS
- Support for multiple POP3 accounts via environment variables
- Automatic deletion after successful retrieval
2. **Email Forwarding**
- Forward emails to Gmail via SMTP
- Preserve original email metadata (sender, date, subject)
- Use Gmail App Passwords for authentication
3. **Scheduling & Automation**
- Periodic checking at configurable intervals (default: 5 minutes)
- Automatic startup and continuous operation
4. **Throttling & Rate Limiting**
- Configurable emails per minute limit (default: 10/min)
- Prevent Gmail quota issues
- Smart delay insertion between sends
5. **Error Handling & Notifications**
- Comprehensive logging (INFO, WARNING, ERROR levels)
- Error notifications via Postmarkapp SMTP
- Graceful handling of connection failures
6. **Docker Deployment**
- Dockerfile for containerization
- docker-compose.yml for easy deployment
- Non-root user for security
- Automatic restart on failure
7. **Configuration Management**
- Environment variable-based configuration
- .env.example template
- Support for unlimited POP3 accounts
8. **Documentation**
- Comprehensive README with setup instructions
- Configuration guide
- Troubleshooting section
- Security best practices
## MVP Validation Criteria
- [x] Successfully fetches emails from at least one POP3 account
- [x] Forwards emails to Gmail without data loss
- [x] Runs continuously in Docker container
- [x] Handles errors without crashing
- [x] Sends error notifications
- [x] Respects rate limits
- [x] Complete documentation for setup
## What's NOT in MVP
- Web UI for configuration
- Database for tracking processed emails
- Advanced filtering rules
- Email archiving
- Multiple destination addresses
- OAuth2 authentication
- Webhook notifications
- Metrics dashboard
- Email deduplication
- Custom retry policies
## Success Metrics
1. **Reliability**: 99%+ uptime for email forwarding
2. **Performance**: Process emails within 1 minute of receipt
3. **Scalability**: Support at least 10 POP3 accounts
4. **Usability**: Setup time under 10 minutes
5. **Security**: No credentials stored in code or logs
## MVP Timeline
- **Phase 1 - Core Functionality** (Completed)
- POP3 fetching
- SMTP forwarding
- Basic error handling
- **Phase 2 - Production Ready** (Completed)
- Docker containerization
- Error notifications
- Throttling
- Comprehensive logging
- **Phase 3 - Documentation** (Completed)
- README
- Configuration guide
- MVP plan
- Roadmap
## Next Steps (Post-MVP)
See [ROADMAP.md](ROADMAP.md) for planned enhancements and future features.
## Known Limitations
1. **Single Destination**: Only one Gmail address supported
2. **No Filtering**: All emails are forwarded without rules
3. **No UI**: Command-line and file-based configuration only
4. **Basic Throttling**: Simple time-based rate limiting
5. **No Retry Logic**: Failed forwards are logged but not retried
6. **No Deduplication**: Same email could be forwarded twice if fetched multiple times
7. **Text Only**: HTML emails are converted to plain text
## Risk Mitigation
| Risk | Mitigation |
|------|------------|
| Gmail rate limits | Configurable throttling, max emails per run |
| POP3 server downtime | Error notifications, automatic retry on next cycle |
| Password exposure | Environment variables, .gitignore for .env |
| Data loss | Delete only after successful forward |
| Container crashes | Docker restart policy |
| Configuration errors | Validation on startup |
## Testing Recommendations
1. **Functional Testing**
- Send test email to POP3 account
- Verify forwarding to Gmail
- Check original metadata preservation
2. **Error Testing**
- Test with invalid credentials
- Test with unreachable POP3 server
- Verify error notifications
3. **Load Testing**
- Test with 50+ emails
- Verify throttling works
- Check memory usage
4. **Security Testing**
- Verify SSL/TLS connections
- Check for credential leaks in logs
- Test with non-root user
## User Acceptance Criteria
- [ ] User can configure multiple POP3 accounts via .env file
- [ ] User receives forwarded emails in Gmail within 5 minutes
- [ ] User receives email notification when errors occur
- [ ] User can view logs to troubleshoot issues
- [ ] User can start/stop service with docker-compose
- [ ] Documentation is clear enough for non-technical users
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# Quick Start Guide
Get your POP3 to Gmail forwarder running in under 10 minutes!
## Prerequisites
- Docker and Docker Compose installed
- Gmail account with 2FA enabled
- POP3 email account credentials
## Step-by-Step Setup
### 1. Clone the Repository
```bash
git clone https://github.com/christianlouis/pop_puller_to_gmail.git
cd pop_puller_to_gmail
```
### 2. Generate Gmail App Password
1. Visit: https://myaccount.google.com/apppasswords
2. Sign in to your Google Account
3. Select "App passwords" under Security
4. Choose "Mail" and "Other (Custom name)"
5. Enter "POP3 Forwarder" as the name
6. Click "Generate"
7. **Copy the 16-character password** (you'll need this in step 3)
### 3. Create Configuration File
```bash
cp .env.example .env
nano .env # or use your preferred editor
```
Edit the following required fields:
```bash
# Your POP3 mailbox
POP3_ACCOUNT_1_HOST=pop.yourprovider.com
POP3_ACCOUNT_1_USER=your-email@provider.com
POP3_ACCOUNT_1_PASSWORD=your-pop3-password
# Your Gmail account
SMTP_USER=youremail@gmail.com
SMTP_PASSWORD=xxxx-xxxx-xxxx-xxxx # The 16-char app password from step 2
GMAIL_DESTINATION=youremail@gmail.com
```
**Important**: Keep the same email for `SMTP_USER` and `GMAIL_DESTINATION`
### 4. Start the Container
```bash
docker-compose up -d
```
### 5. Verify It's Working
Check the logs:
```bash
docker-compose logs -f
```
You should see:
```
pop3-gmail-forwarder | INFO - POP3 to Gmail Forwarder starting...
pop3-gmail-forwarder | INFO - Loaded POP3 account: ...
pop3-gmail-forwarder | INFO - Configuration validated successfully
pop3-gmail-forwarder | INFO - Starting email processing cycle
```
### 6. Test the Forwarder
1. Send a test email to your POP3 account
2. Wait up to 5 minutes (or check the logs)
3. Check your Gmail inbox
4. You should see: `[Fwd from your-email@provider.com] Test Subject`
## Common Issues
### "Username and Password not accepted"
**Problem**: Gmail rejects login
**Fix**:
1. Make sure 2FA is enabled on your Google account
2. Generate a new App Password (don't use your regular Gmail password)
3. Copy it exactly without spaces into `SMTP_PASSWORD`
### "No address associated with hostname"
**Problem**: Can't connect to POP3 server
**Fix**:
1. Verify `POP3_ACCOUNT_1_HOST` is correct
2. Check if POP3 is enabled in your email provider's settings
3. Try port 110 with `POP3_ACCOUNT_1_USE_SSL=false` if port 995 doesn't work
### Container stops immediately
**Problem**: Container exits right after starting
**Fix**:
```bash
# Check logs for errors
docker-compose logs
# Common fixes:
# 1. Check .env file exists and has correct values
# 2. Verify all required fields are set
# 3. Check Docker has internet access
```
## Adding More POP3 Accounts
To forward from multiple email accounts:
```bash
# Edit .env and add more accounts:
POP3_ACCOUNT_2_HOST=pop.another.com
POP3_ACCOUNT_2_USER=user@another.com
POP3_ACCOUNT_2_PASSWORD=another-password
POP3_ACCOUNT_3_HOST=pop.yetanother.com
POP3_ACCOUNT_3_USER=user@yetanother.com
POP3_ACCOUNT_3_PASSWORD=yetanother-password
# Restart the container
docker-compose restart
```
## Managing the Service
```bash
# View logs
docker-compose logs -f
# Stop the service
docker-compose down
# Restart after config changes
docker-compose restart
# Rebuild after code updates
docker-compose up -d --build
```
## Optional: Error Notifications
To receive email alerts when errors occur:
1. Sign up at https://postmarkapp.com (free tier available)
2. Get your Server API Token
3. Add to `.env`:
```bash
POSTMARK_API_TOKEN=your-token-here
POSTMARK_FROM_EMAIL=errors@yourdomain.com
POSTMARK_TO_EMAIL=admin@yourdomain.com
```
4. Restart: `docker-compose restart`
## Customizing Settings
All settings in `.env` can be adjusted:
```bash
# Check every 10 minutes instead of 5
CHECK_INTERVAL_MINUTES=10
# Process up to 100 emails per run
MAX_EMAILS_PER_RUN=100
# Send up to 20 emails per minute
THROTTLE_EMAILS_PER_MINUTE=20
# Enable debug logging
LOG_LEVEL=DEBUG
```
Restart after changes: `docker-compose restart`
## Next Steps
- Read the full [README.md](README.md) for detailed documentation
- Review [MVP.md](MVP.md) for current features
- Check [ROADMAP.md](ROADMAP.md) for planned features
## Need Help?
- Open an issue: https://github.com/christianlouis/pop_puller_to_gmail/issues
- Check existing discussions
- Review troubleshooting section in README.md
## Success! 🎉
Your POP3 to Gmail forwarder is now running. Emails will be automatically forwarded every 5 minutes (or your configured interval).
**Remember**:
- The forwarder deletes emails from POP3 after successful forwarding
- Check Gmail spam folder if emails don't appear in inbox
- Monitor logs occasionally to ensure everything is working
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# pop_puller_to_gmail
A set of scripts and a docker container that will take over GMail's ability to import POP3 messages from 3rd party mailboxes
# POP3 to Gmail Forwarder
A Docker-based solution that automatically fetches emails from POP3 mailboxes and forwards them to Gmail, replacing Google's discontinued POP3 import feature.
## Features
-**Multiple POP3 Accounts**: Support for unlimited POP3 mailboxes via environment variables
-**Automatic Forwarding**: Sends emails to your Gmail account via SMTP
-**Smart Throttling**: Rate limiting to avoid Gmail quotas (configurable emails per minute)
-**Error Reporting**: Email notifications via Postmarkapp when issues occur
-**Scheduled Polling**: Configurable check intervals (default: every 5 minutes)
-**Docker Ready**: Fully containerized with docker-compose support
-**Secure**: Runs as non-root user, uses SSL/TLS for connections
-**Production Ready**: Comprehensive logging, error handling, and best practices
## Quick Start
### Prerequisites
- Docker and Docker Compose installed
- A Gmail account with [App Password](https://support.google.com/accounts/answer/185833) enabled
- POP3 account credentials
- (Optional) Postmarkapp account for error notifications
### Setup
1. **Clone the repository**
```bash
git clone https://github.com/christianlouis/pop_puller_to_gmail.git
cd pop_puller_to_gmail
```
2. **Configure environment variables**
```bash
cp .env.example .env
# Edit .env with your credentials
nano .env
```
3. **Essential Configuration**
Edit `.env` and set:
```bash
# Your POP3 account(s)
POP3_ACCOUNT_1_HOST=pop.yourprovider.com
POP3_ACCOUNT_1_PORT=995
POP3_ACCOUNT_1_USER=your-email@provider.com
POP3_ACCOUNT_1_PASSWORD=your-password
# Your Gmail SMTP settings
SMTP_USER=your-gmail@gmail.com
SMTP_PASSWORD=your-app-password # Generate at myaccount.google.com/apppasswords
GMAIL_DESTINATION=your-gmail@gmail.com
# Optional: Postmarkapp for error notifications
POSTMARK_API_TOKEN=your-token
POSTMARK_FROM_EMAIL=errors@yourdomain.com
POSTMARK_TO_EMAIL=admin@yourdomain.com
```
4. **Run with Docker Compose**
```bash
docker-compose up -d
```
5. **Check logs**
```bash
docker-compose logs -f
```
## Configuration
### POP3 Accounts
Add multiple POP3 accounts by incrementing the account number:
```bash
POP3_ACCOUNT_1_HOST=pop.provider1.com
POP3_ACCOUNT_1_USER=user1@provider1.com
POP3_ACCOUNT_1_PASSWORD=password1
POP3_ACCOUNT_2_HOST=pop.provider2.com
POP3_ACCOUNT_2_USER=user2@provider2.com
POP3_ACCOUNT_2_PASSWORD=password2
# ... add more as needed
```
### Gmail App Password
1. Go to your Google Account: https://myaccount.google.com/
2. Select Security
3. Under "Signing in to Google," select App Passwords
4. Generate a new app password for "Mail"
5. Use this password in `SMTP_PASSWORD`
### Environment Variables
| Variable | Required | Default | Description |
|----------|----------|---------|-------------|
| `POP3_ACCOUNT_N_HOST` | Yes | - | POP3 server hostname |
| `POP3_ACCOUNT_N_PORT` | No | 995 | POP3 server port |
| `POP3_ACCOUNT_N_USER` | Yes | - | POP3 username |
| `POP3_ACCOUNT_N_PASSWORD` | Yes | - | POP3 password |
| `POP3_ACCOUNT_N_USE_SSL` | No | true | Use SSL/TLS |
| `SMTP_HOST` | No | smtp.gmail.com | SMTP server |
| `SMTP_PORT` | No | 587 | SMTP port |
| `SMTP_USER` | Yes | - | SMTP username |
| `SMTP_PASSWORD` | Yes | - | SMTP password (App Password) |
| `SMTP_USE_TLS` | No | true | Use STARTTLS |
| `GMAIL_DESTINATION` | Yes | - | Destination Gmail address |
| `CHECK_INTERVAL_MINUTES` | No | 5 | How often to check for new mail |
| `MAX_EMAILS_PER_RUN` | No | 50 | Max emails to process per account per run |
| `THROTTLE_EMAILS_PER_MINUTE` | No | 10 | Rate limit for sending emails |
| `POSTMARK_API_TOKEN` | No | - | Postmarkapp API token |
| `POSTMARK_FROM_EMAIL` | No | - | Error notification sender |
| `POSTMARK_TO_EMAIL` | No | - | Error notification recipient |
| `LOG_LEVEL` | No | INFO | Logging level (DEBUG, INFO, WARNING, ERROR) |
## How It Works
1. **Polling**: The application checks configured POP3 mailboxes at regular intervals
2. **Fetching**: Retrieves new emails from each POP3 account
3. **Forwarding**: Sends emails to your Gmail account via SMTP with original metadata preserved
4. **Cleanup**: Deletes emails from POP3 server after successful forwarding
5. **Throttling**: Respects rate limits to avoid Gmail quota issues
6. **Error Handling**: Sends notifications via Postmarkapp if issues occur
## Email Format
Forwarded emails include:
- Original sender information in the subject line: `[Fwd from user@provider.com] Original Subject`
- Header section with original From, Date, Subject, and source account
- Original email body preserved
## Monitoring and Logs
### View logs
```bash
docker-compose logs -f pop3-forwarder
```
### Check container status
```bash
docker-compose ps
```
### Restart the service
```bash
docker-compose restart
```
## Troubleshooting
### Gmail Authentication Issues
**Problem**: "Username and Password not accepted"
**Solution**:
- Ensure 2FA is enabled on your Google account
- Generate an App Password (don't use your regular Gmail password)
- Use the 16-character app password without spaces
### POP3 Connection Issues
**Problem**: "Connection refused" or "SSL error"
**Solution**:
- Verify POP3 server hostname and port
- Check if POP3 is enabled in your email provider settings
- Try with `POP3_ACCOUNT_N_USE_SSL=false` for non-SSL connections (port 110)
### No Emails Being Forwarded
**Problem**: Container runs but no emails are forwarded
**Solution**:
- Check if there are emails in your POP3 mailbox
- Review logs for errors: `docker-compose logs -f`
- Verify `GMAIL_DESTINATION` is correct
- Check Gmail spam folder
### Rate Limiting
**Problem**: "Too many requests" or quota errors
**Solution**:
- Increase `CHECK_INTERVAL_MINUTES`
- Decrease `THROTTLE_EMAILS_PER_MINUTE`
- Reduce `MAX_EMAILS_PER_RUN`
## Security Best Practices
1. **Never commit `.env` file** - It contains sensitive credentials
2. **Use App Passwords** - Don't use your main Gmail password
3. **Rotate credentials regularly** - Update passwords periodically
4. **Enable 2FA** - On all email accounts
5. **Review logs** - Monitor for suspicious activity
6. **Use SSL/TLS** - Keep `USE_SSL` and `USE_TLS` enabled
7. **Limit network access** - Use firewall rules if needed
## Development
### Local Development (without Docker)
```bash
# Create virtual environment
python3 -m venv venv
source venv/bin/activate # On Windows: venv\Scripts\activate
# Install dependencies
pip install -r requirements.txt
# Copy and configure .env
cp .env.example .env
# Edit .env with your settings
# Run the application
python pop3_forwarder.py
```
### Building the Docker Image
```bash
docker build -t pop3-gmail-forwarder .
```
### Running Tests
```bash
# Run with verbose logging
LOG_LEVEL=DEBUG docker-compose up
```
## Architecture
```
┌─────────────────┐
│ POP3 Server 1 │
└────────┬────────┘
│ (Fetch emails)
┌─────────────────┐ ┌──────────────┐ ┌─────────────┐
│ POP3 Server 2 │─────▶│ Forwarder │─────▶│ Gmail │
└─────────────────┘ │ Container │ │ (SMTP) │
│ └──────┬───────┘ └─────────────┘
│ │
┌────────▼────────┐ │
│ POP3 Server N │ │
└─────────────────┘ │
│ (Error notifications)
┌─────────────────┐
│ Postmarkapp │
└─────────────────┘
```
## Contributing
Contributions are welcome! Please:
1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Submit a pull request
## License
MIT License - See LICENSE file for details
## Support
- **Issues**: https://github.com/christianlouis/pop_puller_to_gmail/issues
- **Discussions**: https://github.com/christianlouis/pop_puller_to_gmail/discussions
## Acknowledgments
Built to replace Gmail's discontinued POP3 import feature. Uses industry-standard Python libraries for email handling and Docker for easy deployment.
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# Roadmap
## Vision
Create a robust, scalable, and user-friendly POP3 to Gmail forwarding solution that serves as a complete replacement for Gmail's discontinued POP3 import feature.
---
## Current Status: MVP Complete ✅
The MVP includes:
- Multiple POP3 account support
- Gmail forwarding via SMTP
- Error notifications via Postmarkapp
- Docker deployment
- Rate limiting and throttling
- Comprehensive documentation
---
## Short Term (Next 3 months)
### v1.1 - Enhanced Reliability
**Priority: High**
- [ ] **Persistent State Management**
- SQLite database to track processed emails
- Prevent duplicate forwarding
- Resume after failures
- [ ] **Advanced Retry Logic**
- Exponential backoff for failed forwards
- Dead letter queue for repeatedly failed emails
- Configurable retry attempts
- [ ] **Health Monitoring**
- Health check endpoint for container orchestration
- Prometheus metrics export
- Status dashboard (simple web UI)
- [ ] **Enhanced Error Handling**
- Categorize errors (transient vs permanent)
- Different notification strategies per error type
- Circuit breaker for failing POP3 accounts
### v1.2 - User Experience
**Priority: Medium**
- [ ] **Web Configuration UI**
- Add/remove POP3 accounts without editing files
- Test connections before saving
- View forwarding statistics
- Simple React/Vue.js frontend
- [ ] **Better Logging**
- Structured JSON logging
- Log rotation
- Searchable log viewer
- Export logs for analysis
- [ ] **Email Filtering**
- Basic rules (sender, subject, size)
- Whitelist/blacklist
- Regular expression matching
- Forward only matching emails
---
## Medium Term (3-6 months)
### v2.0 - Advanced Features
**Priority: Medium**
- [ ] **Multiple Destinations**
- Route different POP3 accounts to different Gmail addresses
- CC/BCC support
- Conditional routing based on rules
- [ ] **OAuth2 Support**
- Gmail OAuth2 instead of App Passwords
- More secure authentication
- Better user experience
- [ ] **Attachment Handling**
- Preserve attachments properly
- Size limits
- Virus scanning integration
- Cloud storage integration (Google Drive)
- [ ] **Advanced Throttling**
- Per-account rate limits
- Time-of-day scheduling
- Burst mode support
- Gmail quota monitoring
### v2.1 - Email Management
**Priority: Low**
- [ ] **Email Archiving**
- Optional local backup before forwarding
- Export to mbox format
- Search archived emails
- Retention policies
- [ ] **HTML Email Support**
- Preserve HTML formatting
- Inline images
- CSS processing
- [ ] **Email Threading**
- Maintain conversation threads
- In-Reply-To headers
- References preservation
---
## Long Term (6-12 months)
### v3.0 - Enterprise Features
**Priority: Low**
- [ ] **Multi-tenancy**
- Support multiple users/teams
- Per-user configuration
- User management
- API for integration
- [ ] **High Availability**
- Kubernetes deployment manifests
- Horizontal scaling
- Leader election for distributed deployment
- Failover support
- [ ] **Advanced Security**
- Secrets management (Vault integration)
- Encryption at rest
- Audit logging
- SSO/SAML support
- [ ] **Compliance**
- GDPR compliance features
- Email retention policies
- Data export capabilities
- Privacy controls
### v3.1 - Integration & Extensibility
**Priority: Low**
- [ ] **Webhook Support**
- Notify external systems on events
- Custom notification channels (Slack, Discord, Teams)
- Integration with monitoring systems
- [ ] **Plugin System**
- Custom email processors
- Custom notification handlers
- Custom storage backends
- [ ] **API**
- RESTful API for all operations
- Webhook configuration
- Stats and metrics
- Email search
---
## Future Considerations
### Performance Optimizations
- Parallel processing of multiple POP3 accounts
- Connection pooling
- Caching layer
- Batch processing
### Additional Protocols
- IMAP support (not just POP3)
- Exchange/EWS support
- Microsoft Graph API
- Direct Gmail API integration
### Cloud Native Features
- Helm charts for Kubernetes
- Terraform modules
- Cloud provider integrations (AWS SES, SendGrid)
- Serverless deployment option (Lambda, Cloud Functions)
### Machine Learning
- Smart spam filtering
- Email categorization
- Priority detection
- Anomaly detection
### Mobile Support
- React Native mobile app
- Push notifications to mobile devices
- Mobile configuration
- On-the-go management
---
## Community & Ecosystem
### Documentation
- [ ] Video tutorials
- [ ] Interactive setup wizard
- [ ] Migration guides from Gmail POP3 import
- [ ] Best practices guide
- [ ] Performance tuning guide
### Community
- [ ] Discord/Slack community
- [ ] Regular release schedule
- [ ] Contributor guidelines
- [ ] Code of conduct
- [ ] Security disclosure policy
### Compatibility
- [ ] Support for more email providers
- [ ] Test suite for major POP3 providers
- [ ] Compatibility matrix
- [ ] Provider-specific configurations
---
## Release Schedule
- **v1.1**: +1 month (Enhanced Reliability)
- **v1.2**: +2 months (User Experience)
- **v2.0**: +3 months (Advanced Features)
- **v2.1**: +4 months (Email Management)
- **v3.0**: +6 months (Enterprise Features)
- **v3.1**: +9 months (Integration & Extensibility)
---
## Contributing
We welcome contributions! Areas where help is needed:
1. **Testing**: Help test with different email providers
2. **Documentation**: Improve guides and tutorials
3. **Features**: Implement items from the roadmap
4. **Bug Fixes**: Fix issues as they arise
5. **Performance**: Optimize slow operations
6. **Security**: Security audits and improvements
See [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines.
---
## Feedback
This roadmap is a living document. We welcome feedback:
- Open an issue with suggestions
- Join discussions in GitHub Discussions
- Propose new features via pull requests
- Vote on existing feature requests
---
## Decision Framework
Features are prioritized based on:
1. **User Impact**: How many users benefit?
2. **Complexity**: Development and maintenance effort
3. **Security**: Does it improve security?
4. **Reliability**: Does it improve reliability?
5. **Community Requests**: What are users asking for?
---
*Last Updated: 2026-02-01*
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version: '3.8'
services:
pop3-forwarder:
build: .
container_name: pop3-gmail-forwarder
restart: unless-stopped
env_file:
- .env
environment:
- LOG_LEVEL=${LOG_LEVEL:-INFO}
- CHECK_INTERVAL_MINUTES=${CHECK_INTERVAL_MINUTES:-5}
- MAX_EMAILS_PER_RUN=${MAX_EMAILS_PER_RUN:-50}
- THROTTLE_EMAILS_PER_MINUTE=${THROTTLE_EMAILS_PER_MINUTE:-10}
volumes:
# Optional: mount for logs if you want persistent logging
- ./logs:/app/logs
logging:
driver: "json-file"
options:
max-size: "10m"
max-file: "3"
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#!/usr/bin/env python3
"""
POP3 to Gmail Forwarder
Fetches emails from POP3 mailboxes and forwards them to Gmail
"""
import os
import sys
import time
import poplib
import smtplib
import logging
import json
from email import parser
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.utils import formatdate, make_msgid
from datetime import datetime
from typing import List, Dict, Optional
import schedule
from dotenv import load_dotenv
import ssl
# Load environment variables
load_dotenv()
# Configure logging
log_level = os.getenv('LOG_LEVEL', 'INFO')
logging.basicConfig(
level=getattr(logging, log_level),
format='%(asctime)s - %(name)s - %(levelname)s - %(message)s',
handlers=[
logging.StreamHandler(sys.stdout)
]
)
logger = logging.getLogger(__name__)
class ThrottleManager:
"""Manages email sending throttling"""
def __init__(self, emails_per_minute: int = 10):
self.emails_per_minute = emails_per_minute
self.send_times = []
def wait_if_needed(self):
"""Wait if we've hit the throttle limit"""
now = time.time()
# Remove send times older than 1 minute
self.send_times = [t for t in self.send_times if now - t < 60]
if len(self.send_times) >= self.emails_per_minute:
sleep_time = 60 - (now - self.send_times[0]) + 1
if sleep_time > 0:
logger.info(f"Throttling: sleeping for {sleep_time:.1f} seconds")
time.sleep(sleep_time)
self.send_times = []
self.send_times.append(now)
class POP3Account:
"""Represents a POP3 account configuration"""
def __init__(self, account_num: int):
prefix = f"POP3_ACCOUNT_{account_num}_"
self.host = os.getenv(f"{prefix}HOST")
self.port = int(os.getenv(f"{prefix}PORT", "995"))
self.user = os.getenv(f"{prefix}USER")
self.password = os.getenv(f"{prefix}PASSWORD")
self.use_ssl = os.getenv(f"{prefix}USE_SSL", "true").lower() == "true"
self.account_num = account_num
def is_valid(self) -> bool:
"""Check if account configuration is valid"""
return bool(self.host and self.user and self.password)
def __str__(self):
return f"POP3Account({self.user}@{self.host})"
class EmailForwarder:
"""Main class for forwarding emails from POP3 to Gmail"""
def __init__(self):
self.smtp_host = os.getenv('SMTP_HOST', 'smtp.gmail.com')
self.smtp_port = int(os.getenv('SMTP_PORT', '587'))
self.smtp_user = os.getenv('SMTP_USER')
self.smtp_password = os.getenv('SMTP_PASSWORD')
self.smtp_use_tls = os.getenv('SMTP_USE_TLS', 'true').lower() == 'true'
self.gmail_destination = os.getenv('GMAIL_DESTINATION')
self.max_emails_per_run = int(os.getenv('MAX_EMAILS_PER_RUN', '50'))
self.throttle = ThrottleManager(
int(os.getenv('THROTTLE_EMAILS_PER_MINUTE', '10'))
)
self.postmark_token = os.getenv('POSTMARK_API_TOKEN')
self.postmark_from = os.getenv('POSTMARK_FROM_EMAIL')
self.postmark_to = os.getenv('POSTMARK_TO_EMAIL')
# Load POP3 accounts
self.pop3_accounts = self._load_pop3_accounts()
def _load_pop3_accounts(self) -> List[POP3Account]:
"""Load all configured POP3 accounts"""
accounts = []
for i in range(1, 100): # Support up to 99 accounts
account = POP3Account(i)
if account.is_valid():
accounts.append(account)
logger.info(f"Loaded POP3 account: {account}")
elif i == 1:
# At least first account must be configured
logger.error("No POP3 accounts configured!")
break
else:
# No more accounts
break
return accounts
def fetch_emails_from_pop3(self, account: POP3Account) -> List[bytes]:
"""Fetch emails from a POP3 account"""
emails = []
try:
logger.info(f"Connecting to {account}")
# Connect to POP3 server
if account.use_ssl:
pop_conn = poplib.POP3_SSL(account.host, account.port)
else:
pop_conn = poplib.POP3(account.host, account.port)
# Login
pop_conn.user(account.user)
pop_conn.pass_(account.password)
# Get message count
num_messages = len(pop_conn.list()[1])
logger.info(f"Found {num_messages} messages in {account}")
# Fetch emails (limit to max_emails_per_run)
for i in range(1, min(num_messages + 1, self.max_emails_per_run + 1)):
try:
# Retrieve message
response, lines, octets = pop_conn.retr(i)
email_data = b'\r\n'.join(lines)
emails.append(email_data)
# Delete from server after successful retrieval
pop_conn.dele(i)
logger.info(f"Retrieved and deleted message {i} from {account}")
except Exception as e:
logger.error(f"Error retrieving message {i} from {account}: {e}")
pop_conn.quit()
except Exception as e:
logger.error(f"Error fetching from {account}: {e}")
self.send_error_notification(f"POP3 fetch error from {account}", str(e))
return emails
def forward_email(self, email_data: bytes, source_account: str) -> bool:
"""Forward an email to Gmail"""
try:
# Parse the email
msg = parser.BytesParser().parsebytes(email_data)
# Create a new message for forwarding
forward_msg = MIMEMultipart('mixed')
forward_msg['From'] = self.smtp_user
forward_msg['To'] = self.gmail_destination
forward_msg['Date'] = formatdate(localtime=True)
forward_msg['Message-ID'] = make_msgid()
# Preserve original subject with prefix
original_subject = msg.get('Subject', 'No Subject')
forward_msg['Subject'] = f"[Fwd from {source_account}] {original_subject}"
# Add original headers as reference
header_info = f"Originally from: {msg.get('From', 'Unknown')}\n"
header_info += f"Original Date: {msg.get('Date', 'Unknown')}\n"
header_info += f"Original Subject: {original_subject}\n"
header_info += f"Source POP3 Account: {source_account}\n"
header_info += "-" * 50 + "\n\n"
# Get the email body
body = ""
if msg.is_multipart():
for part in msg.walk():
if part.get_content_type() == "text/plain":
body = part.get_payload(decode=True).decode('utf-8', errors='ignore')
break
else:
body = msg.get_payload(decode=True).decode('utf-8', errors='ignore')
# Combine header info and body
full_body = header_info + body
forward_msg.attach(MIMEText(full_body, 'plain', 'utf-8'))
# Send via SMTP
self.throttle.wait_if_needed()
server = None
try:
if self.smtp_use_tls:
server = smtplib.SMTP(self.smtp_host, self.smtp_port)
server.starttls()
else:
server = smtplib.SMTP_SSL(self.smtp_host, self.smtp_port)
server.login(self.smtp_user, self.smtp_password)
server.send_message(forward_msg)
logger.info(f"Successfully forwarded email to {self.gmail_destination}")
return True
finally:
if server:
try:
server.quit()
except Exception:
pass # Ignore errors during cleanup
except Exception as e:
logger.error(f"Error forwarding email: {e}")
self.send_error_notification("Email forwarding error", str(e))
return False
def send_error_notification(self, subject: str, error_message: str):
"""Send error notification via Postmarkapp"""
if not self.postmark_token or not self.postmark_from or not self.postmark_to:
logger.warning("Postmark not configured, skipping error notification")
return
try:
import http.client
conn = http.client.HTTPSConnection("api.postmarkapp.com")
payload = json.dumps({
"From": self.postmark_from,
"To": self.postmark_to,
"Subject": f"[POP3 Forwarder Alert] {subject}",
"TextBody": f"Error occurred at {datetime.now().isoformat()}\n\n{error_message}",
"MessageStream": "outbound"
})
headers = {
'Accept': 'application/json',
'Content-Type': 'application/json',
'X-Postmark-Server-Token': self.postmark_token
}
conn.request("POST", "/email", payload, headers)
res = conn.getresponse()
data = res.read()
if res.status == 200:
logger.info("Error notification sent via Postmark")
else:
logger.error(f"Failed to send Postmark notification: {data.decode('utf-8')}")
except Exception as e:
logger.error(f"Error sending Postmark notification: {e}")
def process_all_accounts(self):
"""Process all configured POP3 accounts"""
logger.info("=" * 60)
logger.info("Starting email processing cycle")
logger.info("=" * 60)
total_forwarded = 0
for account in self.pop3_accounts:
try:
emails = self.fetch_emails_from_pop3(account)
logger.info(f"Fetched {len(emails)} emails from {account}")
for email_data in emails:
if self.forward_email(email_data, str(account)):
total_forwarded += 1
except Exception as e:
logger.error(f"Error processing account {account}: {e}")
self.send_error_notification(f"Account processing error: {account}", str(e))
logger.info(f"Processing cycle complete. Forwarded {total_forwarded} emails total.")
logger.info("=" * 60)
def validate_configuration(self) -> bool:
"""Validate that required configuration is present"""
errors = []
if not self.smtp_user:
errors.append("SMTP_USER not configured")
if not self.smtp_password:
errors.append("SMTP_PASSWORD not configured")
if not self.gmail_destination:
errors.append("GMAIL_DESTINATION not configured")
if not self.pop3_accounts:
errors.append("No POP3 accounts configured")
if errors:
for error in errors:
logger.error(f"Configuration error: {error}")
return False
logger.info("Configuration validated successfully")
return True
def main():
"""Main entry point"""
logger.info("POP3 to Gmail Forwarder starting...")
forwarder = EmailForwarder()
# Validate configuration
if not forwarder.validate_configuration():
logger.error("Configuration validation failed. Exiting.")
sys.exit(1)
# Get check interval
check_interval = int(os.getenv('CHECK_INTERVAL_MINUTES', '5'))
logger.info(f"Will check for new emails every {check_interval} minutes")
# Run immediately on startup
forwarder.process_all_accounts()
# Schedule periodic checks
schedule.every(check_interval).minutes.do(forwarder.process_all_accounts)
# Main loop
logger.info("Entering main scheduling loop...")
while True:
try:
schedule.run_pending()
time.sleep(1)
except KeyboardInterrupt:
logger.info("Received shutdown signal, exiting...")
break
except Exception as e:
logger.error(f"Error in main loop: {e}")
forwarder.send_error_notification("Main loop error", str(e))
time.sleep(60) # Wait a minute before retrying
if __name__ == "__main__":
main()
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schedule==1.2.0
python-dotenv==1.0.0