[crematoria]

What metadata has yet to and can be encrypted? The recipient, the send time and the message size seem impossible to encrypt.

[prophesi]

I think the better question is, "What could count as metadata that we don't have to encrypt?"

But to answer yours: https://github.com/vuvuzela/vuvuzela

Encrypting metadata is a huge challenge. In the meantime, our best bet is to use open-source systems that we know won't be harvesting metadata.