observantTrapezium

You can’t successfully use a home email server.

Mostly true (server can be home but using the ISP network directly probably won’t work)

You can’t successfully use an email server on a (cloud) VPS.

Bullshit

You can’t successfully use an email server on a bare metal machine in your own datacenter.

Bullshit

As such, it is my distinct displeasure to declare the death of SMTP. The protocol is no longer usable. And as we can see, this devolution occurred organically.

Bullshit

Also note that if it’s just for personal use, you don’t have to have a domain for HTTPS. You can self sign, or create your own certificate authority, you just need to clients to trust it. But domains can be cheap or even free, so it’s better to get one so you don’t have to specially configure your devices.

Borg for backup. I’m really surprised it’s not more widely known. It’s an incredible piece of software.

Also, not really lesser known software, but a lesser known feature of file systems including the ones we use in FOSS operating systems: extended file attributes - useful to add metadata to files without modifying them.