Hacker News Reader

There's a reason peer to peer isn't seen as a great idea for messaging and that reason is it's been tried many, many times and it doesn't work well. For some people it just won't work well ever. Furthermore, it doesn't mesh with the expectations most people will have of a mail service (you push the mail out and it will arrive some day regardless of what you do), which makes it a bad fit for the use-case to begin with.

Point to point is very fragile and inflexible.

There are many good reasons for email (and internet in general) was designed to be routable.

That shouldn't be a problem if it's properly encrypted. The whole internet is routed over various switches owned by various entities.