BillionMail is a self-hosted email server and email marketing solution built for businesses and developers who want full control over their email infrastructure without relying on third-party SaaS platforms. It combines a full mail server stack (Postfix, Dovecot, Rspamd) with newsletter campaign tools and real-time analytics, eliminating monthly fees and vendor lock-in. Designed for ease of use, it offers one-click installation via aaPanel or Docker, making it accessible even to non-experts.
Built with Go and containerized using Docker, BillionMail integrates RoundCube for webmail and supports SMTP, SPF, DKIM, and DMARC for enterprise-grade deliverability. It runs entirely on your own server, ensuring data privacy and scalability for campaigns ranging from small newsletters to high-volume cold email outreach.
What You Get
- Full Mail Server Stack - Includes Postfix (SMTP), Dovecot (IMAP/POP3), and Rspamd (spam filtering) for a complete, self-hosted email infrastructure.
- Unlimited Email Sending - No rate limits or quotas on the number of emails you can send, ideal for cold outreach and large-scale campaigns.
- Real-Time Analytics Dashboard - Track sent volume, deliverability rate, open rate, and click-through rate (CTR) with visual metrics on the homepage.
- Domain Setup with Auto-SSL - Add domains, verify DNS records (SPF, DKIM, DMARC), and auto-enable free SSL certificates for secure email delivery.
- Built-in Newsletter Editor - Write, schedule, and send email campaigns using customizable templates with list and tag segmentation.
- Integrated RoundCube WebMail - Access your email inbox directly through /roundcube/ without needing a separate webmail installation.
Common Use Cases
- Running a paid membership newsletter - A journalist uses BillionMail to send exclusive content to subscribers without paying monthly fees to Mailchimp or Substack.
- Scaling cold email outreach - A SaaS startup sends 50,000+ personalized cold emails monthly using BillionMail’s unlimited sending and deliverability analytics.
- Managing internal corporate email - A small business hosts its own email server with secure IMAP access and spam filtering, avoiding Google Workspace or Microsoft 365 costs.
- Developing an email marketing tool - A developer self-hosts BillionMail to test and extend its API for custom CRM integrations or automated workflows.
Under The Hood
Architecture
- GoFrame-based backend enforces clean separation between API controllers and service layers, with context-aware error handling and localization via shared language contexts
- Modular monorepo structure cleanly divides frontend and backend concerns, enabling independent development and scaling
- Dependency injection is implicitly managed through service imports, with business logic and cross-cutting concerns like file operations and localization encapsulated in dedicated modules
- Frontend and backend are decoupled via well-defined RESTful API contracts, supporting scalable UI development
- AI/ML features are isolated in dedicated service modules with structured data models and file-based persistence, ensuring separation from core email processing
- Docker Compose orchestrates a full mail stack with precise volume and network isolation, demonstrating production-grade infrastructure-as-code design
Tech Stack
- Go powers the backend for high-performance email processing, with custom Docker images for core mail components
- PostgreSQL and Redis are used as primary data stores, configured for socket-based local connectivity and secure environment-driven initialization
- Industry-standard mail infrastructure components (Postfix, Dovecot, Rspamd) are containerized with security hardening and shared secrets for seamless integration
- The system is server-side focused, with no traditional frontend framework, targeting deployment as a robust mail server rather than a user-facing application
Code Quality
- Extensive test coverage spans critical paths including email rendering, cryptographic validation, and mail tracking with thorough edge-case handling
- Strong type safety and structured error handling are maintained through context-aware logging and consistent error propagation
- Clear separation of concerns is evident in the MVC-style architecture and well-organized service modules
- Consistent naming conventions and modular design promote maintainability and reduce coupling between components
- Comprehensive logging and audit trails are embedded in production endpoints, enabling deep diagnostic visibility
What Makes It Unique
- Dynamically configurable API layer using GoFrame enables real-time policy updates without service restarts
- Integrated email delivery diagnostics system captures DSN, relay, and delay metrics with interactive tooltip-based failure analysis
- Domain-specific blacklist auto-scan logic is embedded directly in the service layer for adaptive, real-time abuse filtering
- Lightweight CLI tool paired with Docker automation streamlines deployment of complex mail infrastructure
- Compositional Vue hooks enable reusable, type-safe interfaces for complex mail task monitoring views