You usually can’t fully self-host a mail server (like literally in your house) because most residential ISPs block port 25 to prevent spam/abuse. You can use a third party relay service like what Helm offered, but most people “self host” via a cloud provider or a web host.

Abagail Foy in Prey (2016)

That one chapter in Spec Ops The Line

The scenes where you go back to your childhood home in Wolfenstein The New Colossus

Firewatch

I think that’s what KBin is trying to address.