It sends directly (using TLS) to port 26 on the other "handshake" device i.e. not relaying through any third party such as an ISP. I guess there's some theoret

It sends directly (using TLS) to port 26 on the other "handshake" device i.e. not relaying through any third party such as an ISP. I guess there's some theoretical benefit possible there but if you're worried about your ISP reading your email, just use GPG.