NAPS2 (Not Another PDF Scanner) does exactly one thing, scan stuff, and it does it incredibly well. Bypass all the garbage software that came with your scanner, plus it supports batch processing and profiles.

I prefer Launchy which is very lightweight. But regardless of the tool, this is the best way to navigate your computer. I've literally forgotten how to get around to files and folders without it.

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.

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