If you use this service, and if you don't think your mails are winding up in plain text in an NSA datacenter somewhere, you're a damn fool.
(As the sibling comment notes, I'm talking from the perspective of the end user, not that of a technologist. We need to remember who we're ultimately building these things for...)
Self-hosted services are a significant step forward from the corporate trap of the 2000s. Offering paid hosting plans is the most logical, sustainable revenue source for the companies writing this software.
[Sscene. PM_Tech has phoned his truck driver father]
"*Yes Dad; just build a simple installer to get an email address. An email address...it's like a phone number but letters instead. You know...so the cable company can message you. Well I suppose you could just call them...I don't know, it might take a while to build. You will have to learn programming for a start. I know you are 56. Yes, it will cut into your time for watching sports. I know I am "good" at that "computer stuff" but some guy on HN said this is how you should get an email because he knows how to do it...OK. I will be round for the game. Love to mum."
FYI Any service I have to use that starts with going to GitHUb will be ignored unless
[a] I am trying to learn something from it [b] It is 2048.
The problem is that if you host your own e-mail server, you dramatically increase the chances of some unpatched flaw or tiny messed up configuration file causing the Russian mafia to get access to everything on your e-mail server. You probably don't even particularly decrease the risk of the NSA getting your e-mails.
This is a problem that could be fixed by new models for e-mail that utilize encryption so that you inherently don't need to trust third parties in order to make use of their services. Avoiding third parties entirely is very likely impractical and unwise.
How many of them have been compromised by the Russian mafia?
People are so scared of email, and I just don't understand it.
Check out sovereign on github: https://github.com/al3x/sovereign
My point is that taking an inherently insecure (at least with respect to data privacy) protocol like the ones we use for e-mail now and putting it on your own server (and thus taking responsibility for patching, avoiding zero days, etc) is not an answer to the problem of data privacy. The way forward in my opinion is the development of communication protocols which by their very nature are trustless. If you're just interested in protecting content, then if you're using end-to-end encryption, you could use LegitimateBankSiteNumberOne.ru as your e-mail provider and it wouldn't matter. The protocols for doing this are already well-known, it's just a matter of adopting them.
There's also some benefit in avoiding being part of a monoculture. Big mail providers are an enormously interesting target for both spies and criminals. Breaking into random quirky personal servers, though, has a very different cost/benefit ratio.
Are you emailing yourself on a self hosted, air-gapped system?
If you email me for instance, Google has your email shrug.