# posthorn

> Self-hosted email gateway bridging apps to transactional providers (Postmark, Resend, Mailgun, AWS SES, SMTP) with HTTP form, API, and SMTP ingress.

- **Category:** Email
- **Licence:** Apache-2.0
- **Latest version:** v2.0.1
- **Open source:** oss
- **Languages:** Go, MDX
- **Platforms:** Docker Compose, Linux, Podman
- **Tags:** Email, Homelab, Api Gateway, Docker, Go, Self Hosted, Resend, Transactional email, Smtp relay, Contact form, Mailgun, Email gateway, Postmark, Mail Gateway, AWS Ses

## Description

Posthorn is a self-hosted email gateway that connects your self-hosted applications to transactional email providers. It acts as a single outbound mail layer so you don't need to integrate each app separately with external mail services. The software accepts mail through three channels: HTTP form submissions from contact forms, a JSON API for server-to-server calls, and an SMTP listener for apps like Ghost, Gitea, and Mastodon that only speak SMTP. All three channels forward through one of five supported transports. It runs as a single Go binary or Docker container configured with one TOML file. Key capabilities include spam defenses (honeypot, origin checks, rate limits), API key authentication, idempotency for safe retries, Prometheus metrics, health checks, and structured JSON logging. The project is licensed under Apache-2.0.

## Links

- [Homepage](https://github.com/craigmccaskill/posthorn)
- [Website](https://posthorn.dev)
- [Docker](ghcr.io/craigmccaskill/posthorn)
- [GitHub](https://github.com/craigmccaskill/posthorn)

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Source: https://selfhost.directory/project/posthorn