> i say this is the exact reason running your own mail server in 2018 is problematic.
It's a reason why allowing these fairly core services to be provided by a shrinking group of organisations is equally problematic.
Maybe one day Google will decide that they get too much spam from outlook.com (or vice versa) and cut them off too. What are you going to do about it, set up your own mail server? Vote with your feet to another provider? Start a company doing the same? Good luck with that.
It's a reason why allowing these fairly core services to be provided by a shrinking group of organisations is equally problematic.
Maybe one day Google will decide that they get too much spam from outlook.com (or vice versa) and cut them off too. What are you going to do about it, set up your own mail server? Vote with your feet to another provider? Start a company doing the same? Good luck with that.