OTR has nothing to do with encryption. All it says is "pretty please don't save my conversation."
The only way for fully encrypted conversations is to use a plugin that encrypts messages themselves, or use an ecrypted P2P IM network.
The only way for fully encrypted conversations is to use a plugin that encrypts messages themselves, or use an ecrypted P2P IM network.
AFAIK there is no defined standard or agreed-upon XMPP extension for the latter. I should have clarified this in the original comment.