Every product we've built needed email. Transactional emails, welcome emails, password resets, notifications. And every time, we paid through the nose for it.
Resend is great. SendGrid is reliable. But at scale, the costs add up. And more importantly: you're giving control of a critical infrastructure component to a third party.
MailStackOS is our self-hosted alternative.
**The Architecture**
- **Hono API** (edge-compatible): Handles incoming email events, manages queue operations, and exposes a developer-friendly REST API - **BullMQ + Redis**: Reliable job queue for email delivery with retry logic, rate limiting, and dead-letter handling - **Postfix**: Industry-standard MTA running on Hetzner Cloud droplets - **Supabase**: Stores email logs, delivery receipts, and bounce tracking - **Stripe**: Usage-based billing per thousand emails sent
**Why Self-Hosted?**
Control. When your email goes through SendGrid, you're subject to their rate limits, their pricing changes, and their infrastructure is shared with thousands of other senders. IP reputation is a shared resource.
With MailStackOS, you own your sending infrastructure. Your Postfix instance sends from your IP, builds its own reputation, and you control the rate limits.
**Key Features**
- **Domain verification**: DKIM, SPF, and DMARC setup with automated DNS configuration - **Delivery analytics**: Open rates, bounce rates, complaint rates — all tracked in the dashboard - **Bounce handling**: Automatic suppression of addresses that hard bounce - **Webhook events**: Real-time delivery receipts, complaints, and failures - **Multi-domain support**: Send from multiple domains from a single instance - **API-first design**: Everything controllable via REST API or our SDK
**Who It's For**
Teams sending 10K-10M emails/month who want more control over their email delivery. If you're paying $500+/month for SendGrid and want to reduce costs without building from scratch, MailStackOS is the middle ground.
**Pricing**
Self-hosted means you pay for your Hetzner droplet (starting at €3.49/month) plus our platform fee ($0.20 per 1,000 emails sent). For high-volume senders, this is significantly cheaper than SendGrid or Postmark.
Available at mailstack.blueforge.studio.