Many people requested this, and frankly I have no idea why it took me so long, but I've finally built a subscription functionality. I'd be very grateful if people on a variety of email platforms could try it out, and un-spam the emails they receive (since the first few coming from a new domain will invariably tend to end up in the spam box). Soon enough, hopefully, Google and others will learn to trust this email server!
Anyway, the signup url, which is still semi-private, is here. If you hit any errors or have any feedback, please email me.