This maplet application fulfilling the role of the secret key uses base 64 encoding scheme non-linear transformations for encrypting or decrypting e-mailed files. The encrypted files with extension ".e64" contain only 64 characters belonging to the set of base 64 encoding scheme alphabet and 23 characters "()<>[]{}|-*^_!?@#$%&,:;". The application uses original encryption tool named C64K366. The number following the letter "C" means that any encrypted file contains only 64 characters with ASCII decimals belonging to the set {33, 35 .. 38, 40 .. 45, 47 .. 60, 62 .. 91, 93 .. 95, 97 .. 125}. K366 means that the secret key length equals to 366 bits. For proper functioning of the application, the c64k366.maplet must be saved in a location with no spaces in the path name.