# 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