Alas for email
Here's a quote from a recent message from Linus Torvalds to the Git development list:
Now, this is very much a gmail bug, but I've long since given up any hope at all that the gmail people would listen to outsiders (and from my interactions with people inside of google, I think they consider anybody outside the “gmail” team to be outsiders – good luck to any Google people trying to get gmail issues fixed either).
GMail has broken email again, in other words, but rather than avoid GMail, we're simply working around the problem in our other tools. That doesn't seem like a way to keep email working outside of a small group of huge, centralized providers.
The new confidential mode does not seem to be supporting a standards-based, federated system either. Email was once a good thing, but that was a fair while ago at this point, I guess.