E-Mail is one of the last remaining federated systems on the Internet, but I doubt it will survive long as the large players slowly sabotage it. I think already more than 90 % of all e-mails are delivered by three or four large companies, which is a trend that will continue.
But HTTP is client/server whereas e-mail is server/server (or client/server/server/client). Small independent server operators are at the mercy of the large companies as those can just stop processing their e-mails (which they already often do). That's different for HTTP (though gatekeeping happens there too via discoverability and other mechanisms).
Both HTTP and SMTP are client/server because you cannot read SMTP without a "client"... The crucial part of these protocols are simple text that use DNS for distributing the connecting.
HTTP can be used for server to server too... and I recommend it.
So to repeat you need to implement HTTP, SMTP and DNS in you server software so that you can self host all 3 on your own hardware.
This means asking your fiber ISP to open all ports (25, 53, 80) and give you a static IP!
DNS is centralized for now... but eventually it wont be.
I'm not saying you can't do it, I'm saying it won't help you because nobody will want to "play" with you. Open protocols mean nothing if the playing field is not level and the big guys can just bully around smaller players in whichever way they wont. That's not a problem that can be solved by technology (IMHO).
I have my own domains and people play with me all the time?
The big players are going to get pretty mean when electricity costs rise.
So the playing field will level by itself.
I use Raspberry 2/4 in my home cloud that I can keep powered through a 48 hour power failure.
There is no economic power, there is only energy (coal, oil and gas that is turned into electricity (the grid, wind, solar and hydro requires hydrocarbons to make/sustain)); the way to compete is to lower your energy costs by making better systems.
A lot of businesses host their own email, if not on Linux then using Microsoft Exchange (see e.g. [1]). While that is being somewhat decreased by the cloud trend, I don't see it going away, as those businesses generally like keeping their independence.
