A lot of people probably don’t know that Fastmail was started by Jeremy Howard, one of the creators of https://www.fast.ai which is by far the best way to learn deep learning IMHO :)
So many little things are done right, and all with open standards.
I still have fond memories of learning my way around the Fastmail infrastructure while sitting on the couch in your Port Melbourne loungeroom back in 2004. Such a long time ago.