If anyone is currently looking for an encrypted anonymous email service then try riseup mail. It's free, and I would venture to say the best service available. There's also Tormail which is not user friendly in comparison to Riseup mail. There is also Countermail which uses a java plugin to encrypt your communication. Countermail is not free though. Those are the best services I found after researching anonymous encrypted email services about a year ago. That's not to say other great services could have been released since then.
https://mail.riseup.net/http://tormail.org/https://countermail.com/?p=start