Originally Posted by Phaiz
I've never needed to do send money back from donations but I'm fairly certain paypal has all of the info already stored should you need to.
They most likely have, but you don't get access to the IP address that the payment as requested above.
I could imagine that the request was meant if someone issued a charge back with his/her bank, then the IP of the transaction could be used to search through (e.g. a player tracker) to ban that person permanently from the servers for charge backs / fraud, etc. Stuff like that.
It is however technically possible to pass variables through PayPal, which will then be sent back again through the IPN notification system; so it is theoretically possible to make.