[wyager]

I recently switched from gmail to ProtonMail. Not self-hosted, but (theoretically) encrypted while at rest using a GPG key derived from my password. Definitely an improvement. If you really want SMTP, as I understand it they have an "SMTP bridge" software that you host yourself that uses ProtonMail as a backend. Seems like a good compromise. You don't have to worry about constant uptime or disk failure, but your data is still fairly well protected.

[megous]

You probably don't need constant uptime. Sending server will try to deliver for a day or two, usually. Legitimate servers use sending queues.