There is described a computer network system in which a computer is in network communication with a server. In order to install a software package on the computer, installation software forming part of the software package is executed which requests entry of an email address for the user of the software package on the computer. The entered email address is then transmitted to the server, which in response sends an email to the email address including a Uniform Resource Locator (URL) addressing a local web server forming part of the software package, with installation information being appended to the URL. When the user of the computer accesses the URL using a web browser, the local web server automatically sends the installation information to the installation software. In this way, it is established that the user of the software package has access to the entered email address.