User Guide

IPN Testing
IPN Troubleshooting Tips
30 June, 2009 IPN Guide
z Ensure that you are encoding your response string and are using the same character
encoding as the original message.
NOTE: If you receive multiple IPN messages for the same transaction or if messages appear
to be out of order, this is not necessarily an indication that your listener is
malfunctioning. For example, if you do not respond in time, PayPal resends the
message. You should investigate these situations; however, because they could be
caused by a logic errors or performance problems as well.