This SpringerBrief examines the technology of email privacy encryption from its origins to its theoretical and practical details. It explains the challenges in standardization, usability, and trust that interfere with the user experience for software protection. Chapters address the origins of email encryption and why email encryption is rarely used despite the myriad of its benefits -- benefits that cannot be obtained in any other way. The construction of a secure message and its entwining with public key technology are covered. Other chapters address both independent standards for secure...