Email is federated, not point to point. It quite often hops between a couple of servers. Cloud hosted stuff typically gets routed through the cloud provider first (and whatever intelligence agencies are tapping that feed), which then pushes it to the top-tier smtp server nearest the destination for obscure hosts.

Still we’re in a perverse situation here. Running your own server is getting harder to do since everything operates on white lists, and I wouldn’t trust the big name providers for something like this.