This is indeed worrying. I've been running my own E-mail servers for the last 20 years or so and even though my problems weren't as severe, I did run into a few

This is indeed worrying. I've been running my own E-mail servers for the last 20 years or so and even though my problems weren't as severe, I did run into a few cases where the "big ones" were at least delaying my E-mail. But this kind of problem invariably arises when we go from a fragmented Internet with lots of small hosts/providers to an Internet of several walled gardens, run by the big guys. The real answer is to offer a reasonable self-hosting competitor to GMail.