Even if you’re scared of Linux and writing exim.conf, there are more or less turnkey docker containers out there and whatnot too. I can’t recommend one because I think docker is pointless for a single host running a few applications.
The reason I do it is that E-mail is often the only identity on other services I use (it’s often the only way to reset your passwords), and I feel it is too risky to be dependent on a megacorp for my identity, a megacorp who may decide out of the blue to suspend my account for no reason.
I’m dependent on my VPS provider, but I have backups and can take my Debian config with me to a different one. Or bare metal if I have to.
I’m dependent on my DNS registrar and haven’t figured out a good way to mitigate that risk.
Besides that, that’s it.
That plus the fact that the receiver on almost all my emails would be storing them on one of the few big providers and it just never felt worth it.
I have very, very rare deliverability problems, maybe once every two years AT&T decides to block mails from my domain but I resolve it through their easy process.
I have the advantage of having done this for 15 or so years so my IP has some good reputation, but I don’t think IP reputation is really that huge or necessary. The first rule of self hosting Email is “never spam—not even once.” Follow that and you’re in good shape.
However, you do need proof that you 'own' the IP address by means of a reverse IP address. ISPs generally don't allow their customers to set a reverse-DNS record for the IP address, because you do not own the IP. Since most spam originates from botnets from consumer IP addresses, adding the reverse-DNS requirement resulted in a huge reduction in spam.
The email service providers didn't ruin email, spammers did.
They can't or won't.
...and the ones that do are an insignificant drop in the bucket in terms of numbers. Unless "self-hosting" one's digital infrastructure can become easy and off-the-shelf for non-tech folks (or even tech folks that value their time and effort), it just not going to happen.
Right now I am using a set or solutions:
* email * [2]
* files * using NextCloud
* blog * using Hugo
* news * using my own RSS reader
* pihole * to filter things
What I consider to use in the future
* pictures * using photoprism
* citadel * I found some sort of suites like citadel. Not sure if that works, if it is good, or if it fits my needs at all [3]. At the first glance seems like a fun project.
Links:
[1] https://specbranch.com/posts/one-big-server/
[2] https://github.com/LukeSmithxyz/emailwiz
All in all it is time consuming to setup up, and update regularly.
unattended-upgrade does the security upgrades and I occasionally upgrade the rss reader (as it is not packaged)
mail was pretty much fire-and-forget postfix+dovecot on file config, no DB for list of accounts + some catchalls.
If I had to pay say $5 for each of those services vs pay myself to manage that it would more less come out the same, minus ability to fix any little annoyances I had directly vs hoping cloud provider gives an option for it.
I do use syncthing for file sync so no annoying dealings with PHP apps
I think you might have meant distributed and decentralized systems in general. But the answer has nothing to do with technology. We have all the decentralized technology we need (long before blockchain by the way), even e-mail is somewhat decentralized (well, at least distributed), yet it doesn't solve the problem by itself.