An email system with the speed of the USPS, the ease of use of the DMV, the security of the social security system, and the billing of the IRS. It already sounds like a digital gulag, lol
for example, Google could provide the service - but they would have to avoid co-mingling the service with their existing one. They wouldnt have the same rights to the content within the email as they do with a gmail account. And they wouldnt be spam filtering small businesses into oblivion for trying to talk to each other directly.
technically the service can be fulfilled by multiple vendors adhering to the same specification.