I would echo others advice to avoid self-hosting emails, as it’s just impractical and frankly just won’t work properly for reasons you can’t control.
We far as mail providers go, I don’t know if mailbox.org meets your requirements for “encrypted”, but have a look at them.














The impracticality of mail self-hosting has nothing to do with the actual host, or the service on the host. Those are like any other service. It’s about getting others (Google, yahoo, whoever) to accept emails from you and not consider it spam. If they stop accepting mail from you, or never even start, you can’t even do much about it. You might have to write individual requests for basically every major mail host. Mails will fail to send, a lot. So it’s not up to you to fix this when it doesn’t work, you realy on them to white list you. It’s just not gonna work.
As for Mailbox: the “standard” mail plan includes a very small drive-like storage (5 GB I think?), but it’s mostly mail storage (10 GB) and you can add on as many GB as you like (0.20 € each I think).