"AK: Your best bet would surely be to register a callback handler to listen for messages on a specific address?"
Yep - that seems the most obvious method - just wanted to make sure I hadn't missed some other turn of events. With your own callback handler, you can clearly sort out any email encodings, etc.
On the Doco - Goggle doesn't seem to index github io pages. Seems to me you need to have some sort of URL redirect, that looks like say https://smarthome.community/openluup, that would get indexed? ie via the web server set up or similar.