I have advocated for over a decade the creation of an online resource run as part of the post office that would be functionally similar to Facebook, but without the adds.
It might have nominal fees for somethings, but it would be cheaper than delivering things like jury summonses to houses.
Don’t step in and regulate them, just put up a bare bones free one good enough for most people.
It makes sense, and it would be easy. The USPS already offers accounts to track things, so all they'd have to do is expand the current system -- and not by a lot. Provide an account for every U.S. citizen as an electronic address attached to your SS#.
Where I would draw the line is in requiring citizens to sign up. Now you're getting in some spooky territory.