Abstract: Secure software distribution is initiated by sending software media files to a recipient machine as an attachment to an electronic mail message. The software media files include an installation script that copies the program files and creates the icons necessary to run the application. The recipient opens the electronic mail message in his mail folder and clicks on an installation button to activate execution of the installation script. After successful completion of the installation the script is marked “used” and cannot be used again. Marking of the installation script as “used” also disables the forwarding mechanism of the electronic mail software to prevent the user from accessing a second copy of the software. When the recipient saves the electronic mail message, the “used” flag is set and the script can continue. The installation script stores the encrypted hard drive serial number into the system registry.