The e-Capsule? Private Mail is a family of "zero-footprint" secure e-mail clients featuring strong (AES256) encryption of mail boxes and address books, allowing the generation, import and management of personal digital certificates for encrypting and digitally signing e-mails and attachments. Within the e-Capsule? Private Mail product family, the USB-U3 version is directed to owners of a U3 Smart device and users for which simplicity, security and mobility are the fundamental requirements. With a U3 device you can carry your software on the same USB flash drive that carries your files.