This was built for a single person, so I'm fine with having to reauthenticate every week to avoid dealing with extended verification of google dev account. GMail scopes are restricted, so that verification would include a paid security audit - it isn't sustainable for a private project.
Anyone can deploy a fork of this repository to AWS and stay within free tier - essentially for free. If you want to do so, please open an issue - I will update this README with detailed steps.