Deploy and Host Resend SMTP Gateway on Railway

Resend Railway SMTP Gateway is a small Go service that accepts SMTP messages and relays them to Resend via the Resend HTTPS API. It provides a lightweight SMTP endpoint that forwards incoming mail to Resend for delivery, with configuration via environment variables and a container-ready setup.

About Hosting Resend Railway SMTP Gateway

Hosting this gateway on Railway involves building and deploying the Go service as a container or service, providing the required environment variables (notably RESEND_API_KEY), and exposing the service port so Railway routes incoming TCP traffic.

Common Use Cases

• Relay inbound SMTP from internal systems to Resend for centralized email delivery.
• Provide an SMTP endpoint in ephemeral environments (containers) without maintaining a full MTA.
• Test SMTP integrations locally and deploy the same service to production on Railway.

Dependencies for Resend Railway SMTP Gateway Hosting

• A Railway account and project to deploy containers/services.
• A Resend API key (RESEND_API_KEY) with sending permissions.

Deployment Dependencies

• Railway docs: https://docs.railway.app
• Resend API docs: https://resend.com/docs
• Optional SMTP library used in the project: emersion/go-smtp (https://github.com/emersion/go-smtp)

Why Deploy Resend SMTP Gateway on Railway?

Railway doesn't provide an SMTP gateway for non-PRO accounts. This server solves the problem using Resend Gateway.

Railway is a singular platform to deploy your infrastructure stack. Railway will host your infrastructure so you don't have to deal with configuration, while allowing you to vertically and horizontally scale it.

By deploying Resend Railway SMTP Gateway on Railway, you are one step closer to supporting a complete full-stack application with minimal burden. Host your servers, databases, AI agents, and more on Railway.