Dark Mail Alliance, co-founded by Lavabit and Silent Circle, aims to create an open source email protocol and architecture that has end-to-end encryption built-in.
Lavabit LLC is the Texas, US-based company that used to provide secure email services, but was voluntarily shutdown because the owner and operator, Ladar Levison, did not want to hand over private SSL key used to ensure his clients email security to US authorities. It was the email service used by Edward Snowden, the ex-CIA contractor who exposed details about the global and illegal surveillance activities of the NSA.
Silent Circle, headquartered in National Harbor, MD USA, provides a range of secure communication services, but was also forced to voluntarily shutdown its secure, end-user email service for the same reason that Lavabit did.