I enjoyed reading this as well, email has indeed been a very resilient technology for the last 50 years. I've been following https://delta.chat/ for a while, and it's really a clever way to build a service on top of email.

Hi @benwerd and @mapkyca, thanks for your replies, apologies for not having chimed in here for a while. I don't know what happened, but it looks like things are working again. I didn't touch anything as I haven't had time, so either this was just a cache issue on my end, or I was being an idiot (or both!). Thanks for taking a look!