Talking about proprivacy literature under the context of online communication precisely towards email services , following are some of my suggestions . Free , based in Belgium , True endtoend encryption with Digital Signatures Free based in Germany , endtoend encryption Free , based in US , endtoend encryption . Email is however fundamentally not secure and one has to make several tradeoff ' s depending on their personal preferences , specific requirements and understanding of security privacy on the whole . Though their are some projects i n t ernetmailenvironmentmarch 2015 . pdf , , . which are working on reengineering the protocol but that again is workinprogress . I personally use due to their complete emailing suite docs , calendar , address book , groups , polls , IMAP , POP , . and the ability of Digital signatures however , it all depends on individual preferences and specific requirements . Privacy tools and Vegard secure email services feature matrix . are some of the other places that provides further details in this regard .