Sure, you may run a mail server next to the dryer, but who knows where your mail is, or how it got there.
The internet is not about point-to-point communication. It's a *publishing* technology. The reason I can see this Slashdot page is because it was published on some servers, not sent over some secure wire to me. I click on a URL and somewhere a server sends the data comprising that page out into the net, broken up in itty-bit packets with my IP address embedded in them, and eventually they all get to me, where they are reconstructed and displayed in my browser.
Email is no different. Sure, you can use encryption. But, that's self-limiting unless the entire world knows everyone else's key, and then what good would encryption be?
Just as criminals rely on "social engineering" to get access to data, it's been used for centuries by governments and others to get access to data other people do not want them to see. No matter how anyone uses technology to secure their internet "privacy" (quotes because it's an oxymoron), you are really just depending that the folks who create the technology have not been "socially engineered".
So... if you don't want someone to find out something, don't publish it, on the net or elsewhere.