- May 29, 2010
Wouldn't anyone you contact with E2E enabled who doesn't have it just see a bunch of seemingly random garbage text?But you can't ensure that everyone you contact uses it as well. Unless the developer explicitely makes the program XMPP-incompatible or does not implement server-to-server communication and enforces your server you can use it to chat with every other XMPP-based communication system. See the history of the Facebook chat and Google Talk for some examples.
If the client does not enforce E2E and throws an error on trying to contact anyone who does not use a client that supports the same extension, you might not be using any kind of encryption at all without noticing it.