Paypal Instant Payment Notification (IPN) history
https://www.paypal.com/cgi-bin/webscr?cmd=_display-ipns-history
For Paypal Australia
https://www.paypal.com/au/cgi-bin/webscr?cmd=_display-ipns-history
Settings > My Selling Tools > Instant Payment Notifications click "Update". You will see a link there called "IPN History page".