The paper presents a technique based on public key cryptography that allows electronic mail systems to hide the identities of participants and the content of communications, even in an unsecured telecommunication system. This method does not require a universally trusted authority and enables one correspondent to remain anonymous while allowing the other to respond via an untraceable return address. The technique can also be used to form rosters of untraceable digital pseudonyms, allowing individuals to correspond with record-keeping organizations under unique pseudonyms. The paper introduces the concept of a "mix" computer that processes mail items to hide correspondences between inputs and outputs, ensuring that no item is processed more than once. It also discusses the use of untraceable return addresses and certified mail, as well as the creation of digital pseudonyms through a roster system. The system can be adapted for elections and other applications, providing limited anonymity and security.The paper presents a technique based on public key cryptography that allows electronic mail systems to hide the identities of participants and the content of communications, even in an unsecured telecommunication system. This method does not require a universally trusted authority and enables one correspondent to remain anonymous while allowing the other to respond via an untraceable return address. The technique can also be used to form rosters of untraceable digital pseudonyms, allowing individuals to correspond with record-keeping organizations under unique pseudonyms. The paper introduces the concept of a "mix" computer that processes mail items to hide correspondences between inputs and outputs, ensuring that no item is processed more than once. It also discusses the use of untraceable return addresses and certified mail, as well as the creation of digital pseudonyms through a roster system. The system can be adapted for elections and other applications, providing limited anonymity and security.