There are still new email providers appearing every few years right? What special incantations are they performing to be allowed in the club? Do they buy large IP ranges? Do they pay protection money to Google et al?
They buy their own IP range, establish their own AS, and pay for peering/bandwidth as an independent network and not as a single user/customer on someone else's network.
This is fairly straightforward to do, but requires more commitment than renting some CPU time and bandwidth on someone else's machine.
