Design Fundamentals of Hugo-mx-gateway

hugo-mx-gateway is built upon a simple request handling workflow:

Create an HTML form with a POST action pointing towards the hugo-mx-gateway service. This service enables a RESTful POST endpoint backed by an application built in Go. The application is released as container image along with manifests to ease deployment on Google App Engine, Kubernetes, and Docker environments.
For each user request, hugo-mx-gateway automatically retrieves information submitted by the user (email, subject, message details...), then generates and sends a templated email (based on Go Template) to the user-provided email address, while bccing a copy of that email to an address that you can define for internal tracking and follow up.
Once a request is processed (upon success or failure), hugo-mx-gateway handles the reply back towards the calling static page by redirecting the browser to the origin page with additional URL parameters describing the completion status of the processing (e.g. /contact.html?status=success&message=request%20submitted). The parameters can then be easily retrieved and shown to the user, e.g. with a few lines of Javascript within the static page.
The project is shipped with a sample HTML form intending to cover a basic use case of contact and demo requests. That said, this is a open source software, so you're free to adapt it for your specific use cases.