Inboxen

Inboxen is a self‑hosted, privacy‑centric email aliasing service that lets developers expose an infinite number of disposable inboxes behind a single account. From a technical standpoint, it operates as a microservice that intercepts incoming SMTP traffic, routes messages to user‑specific aliases, and exposes a RESTful API for CRUD operations on inboxes. The application is built with Go for the core server, leveraging its concurrency model to handle thousands of simultaneous mail streams. A lightweight PostgreSQL database stores user metadata, alias mappings, and message headers, while a Redis cache is used for rate‑limiting and session tokens. The front end is a single‑page React application that communicates with the Go backend over HTTPS, providing a responsive UI for inbox creation and message management.

Key Features

• Alias Generation: Uses a deterministic algorithm (hash(email+counter)) to create unique, non‑reusable addresses that never collide.
• Minimal Data Retention: Only stores message headers and optional body snippets; attachments are streamed directly to the user’s chosen storage backend (local disk or S3).
• Export & Deletion: Exposes endpoints to export all messages in JSON or CSV and to permanently delete an account, guaranteeing data erasure.
• Webhooks & API: Supports inbound webhooks for external services (e.g., Zapier, IFTTT) and a public API that allows programmatic inbox creation, listing, and message retrieval.

Technical Stack

The Go service is split into three packages: mail (SMTP handling), api (REST routes), and storage (database abstractions). The use of interfaces for storage allows swapping PostgreSQL with a pure‑Go key/value store if desired.

Deployment & Infrastructure

Inboxen is designed for containerized environments. A single Docker image contains the Go binary and a Postfix configuration that forwards mail to the listener on port 2525. The Compose file defines three services: inboxen, db (PostgreSQL), and redis. For production, the image can be deployed to Kubernetes with a StatefulSet for PostgreSQL and a Deployment for Inboxen, exposing an Ingress with TLS termination. The application scales horizontally by adding more inboxen replicas; the Postgres database becomes the single point of contention, so read replicas or sharding can be introduced for high‑traffic scenarios.

Integration & Extensibility

Inboxen’s plugin architecture is minimal but powerful: developers can implement new authentication backends by providing a AuthProvider interface. The public API follows OpenAPI 3.0, making it easy to generate SDKs in any language. Webhooks are configurable per inbox, enabling automatic forwarding to third‑party services or custom Lambda functions. The React front end is modular; developers can fork the repo and replace UI components without touching the backend.

Developer Experience

The project is licensed under AGPLv3, ensuring that any derivative work remains open. Documentation includes a comprehensive developer guide, API reference, and deployment tutorials. The community is active on GitHub Discussions and a dedicated Slack channel where contributors discuss feature requests and bug fixes. Configuration is handled via environment variables, with sensible defaults that allow a quick “docker run” start‑up.

Use Cases

• Privacy‑Focused SaaS: Companies can provide customers with disposable inboxes to protect their real email addresses during sign‑ups.
• Testing Environments: QA teams can generate temporary aliases to test email workflows without polluting real inboxes.
• Automation Pipelines: Integrate with CI/CD tools to capture notification emails or verification links.
• Data Collection: Collect user data from email replies while maintaining anonymity for the sender.

Advantages

Inboxen offers a lightweight, performance‑optimized alternative to full‑blown mail servers like Postfix + Dovecot. Its Go implementation handles high concurrency with minimal memory footprint, while the AGPLv3 license guarantees that improvements remain open. The combination of a minimal data model, robust API, and container‑friendly deployment makes it an attractive choice for developers who need a secure, scalable email aliasing solution without the overhead of traditional mail server stacks.