Email is decentralized because Gmail, Yahoo Mail, Hotmail and whatever server you can setup can talk together. You don't have to use Gmail to send an email to a Gmail user.
The only thing that's threatening email decentralization is the war on spam. It's becoming more and more difficult to send messages that don't go directly to spam boxes if you're not one of the big player.
The only thing that's threatening email decentralization is the war on spam. It's becoming more and more difficult to send messages that don't go directly to spam boxes if you're not one of the big player.