Automatically email me when someone opens an Excel File

I would like to be emailed whenever an Excel file that I write is opened; the user will have enabled auto-executing macros, so that is not a problem. In other words, when a file that I give to one of my clients is opened, I will know how often, and who, has used it. Deliverable will be an autoexecuting macro that I paste into my application ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Installation package that will install the software (in ready-to-run condition) on the platform(s) specified in this bid request. 3) Exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform Windows