BostonHacks' SendGrid Inbound Parse webhook. This repository is a good example of using Inbound Parse to route emails from a domain to specific individuals.
The function code/devependencies are inside functions. Make sure to run npm install inside that folder. To use the email tester, run npm install at root. To deploy, you'll need the Firebase CLI, install with npm install -g firebase-tools. Then run firebase login to authenticate. When ready to deploy, run firebase deploy --only functions from the project root.