I am developing a document transfer web app where by clients can upload/download documents via hyperlinks.My problem is, not knowing if/when any client has downloaded a particular document and hense enable me to remove the document (I need to do this to free up limited(expensive!) space on my ISP's server). Is there any mechanism I can use to 'notify me' when they have downloaded a file (other than the client emailing me! - not really what I want). The site is based on an Apache server, and I'm using PHP/Mysql.