SimpleRelay: Take Back Control of Your Email Delivery

Let's be honest — email delivery is broken for most small teams. You're either paying through the nose for services like SendGrid or Mailgun, fighting with complex API integrations, or watching your transactional emails land in spam folders. It's 2024, and we shouldn't need a computer science degree just to send a password reset email.

That's where SimpleRelay comes in, and honestly, it's refreshing to see a project that keeps things genuinely simple.

What Is SimpleRelay?

SimpleRelay is a self-hosted SMTP relay solution that puts you back in the driver's seat. Built on a solid foundation of FastAPI, Postfix, and Docker, it gives you a complete email relay infrastructure without the vendor lock-in or monthly bills.

The project, maintained by the toinbox organization on GitHub, is designed for developers and teams who want full control over their email infrastructure without sacrificing usability.

Key Features That Actually Matter

Web Dashboard for Management

One of the most pain points with traditional Postfix setups is the lack of a user-friendly interface. SimpleRelay wraps everything in a clean web dashboard where you can:

• Monitor email queues in real-time
• View delivery status and logs
• Manage sender credentials
• Configure relay settings without touching config files

This is huge for teams where not everyone is comfortable editing Postfix configuration files at 2 AM.

DNS Validation for Sender Domains

Email authentication has become non-negotiable. SimpleRelay includes DNS validation to ensure your sender domains are properly configured with SPF, DKIM, and other records. This helps you:

• Catch configuration errors before they cause deliverability issues
• Maintain proper email authentication standards
• Reduce the risk of your emails being flagged as spam

The validation happens automatically, giving you peace of mind that your domain setup is solid.

Per-Sender Access Control

This is where SimpleRelay really shines for multi-tenant or multi-project scenarios. You get granular control over which senders can use the relay and where they can send. Need to restrict a particular API key to only send to specific domains? No problem. Want to isolate different projects from each other? SimpleRelay has you covered.

This level of control is typically only found in enterprise email solutions — now it's available in a self-hosted package.

Why Self-Hosted Email Infrastructure?

You might be wondering: why not just use SendGrid or Amazon SES? Fair question. Here's why self-hosted makes sense for many use cases:

Cost Control: No per-email fees or tiered pricing structures. Your infrastructure costs are predictable and often significantly lower at scale.

Data Sovereignty: Your emails stay on your servers. For businesses with strict data compliance requirements, this isn't optional.

Customization: Need to integrate with custom authentication systems or add specialized logging? With self-hosted, you own the code.

No Rate Limits: Well, technically you have rate limits, but they're your limits. Want to send 10,000 emails in an hour? Configure your server accordingly.

Getting Started with Docker

SimpleRelay ships with Docker support out of the box, which means getting running takes minutes rather than hours of dependency management. The team has clearly thought about the developer experience — the setup process is straightforward, and the documentation walks you through common deployment scenarios.

Whether you're deploying on a VPS, a dedicated server, or within a Kubernetes cluster, SimpleRelay adapts to your infrastructure needs.

The Bottom Line

SimpleRelay represents a growing trend in the developer community: taking back control from SaaS vendors where it makes sense. Email infrastructure is complex, but it doesn't have to be inaccessible. With the right tools and a focus on usability, self-hosted email relays are becoming viable options for teams of all sizes.

If you've been frustrated by email service costs, locked into proprietary APIs, or just want more control over your email infrastructure, SimpleRelay deserves a spot on your evaluation list.

Check out the project on GitHub and see if self-hosted SMTP relay is right for your next project.

What email delivery challenges have you faced? Share your experiences in the comments below.