get ip address from email

I need a piece of code that will get the users ip address and send it back to the sender of the original email. So, I send email, user opens email, a receipt gets sent back with the users ip and time they opened it. ## 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) Complete ownership and distribution copyrights to all work purchased. ## Platform anything