Is there a software where people can chat individually and in a group, but without a center server, and all communication transferred via users' email?
For example, when a user talks with another user, what actually happens is that an email was sent. When a user joins a chatroom, the mechanism is that everyone else in this chatroom receives an email notifying that a new user is in.
I guess someone should have built such a software, since it requires no special servers, but makes use of the existing ones for email.
(Maybe plugins for digsby & pidgin?)
I wish it open-source and HTML & JS based (c.f. Electron), so that it is easier to be ported into various platforms.