PayPal has finally posted public acknowledgment of this ongoing issue at
Merchant Technical Services Notification
This notification is designed to inform you of the
following ON-GOING IPN issue:
- PayPal Live Site
- Order Management (IPN / PDT)
- May 15, 2008 6:00 AM PDT (May 15, 2008 2:00 PM BST)
During this time some merchants may be receiving an INVALID response for some IPNs. Our technical teams are working diligently to resolve the
issue. We will provide updates until the issue is resolved.
From approximately May 16, 2008 10:57 AM PDT (May 16, 2008 6:57 PM BST) to
May 16, 2008 2:58 PM PDT (May 16, 2008 10:58 PM BST) we experienced intermittent
delays with IPN as well, not related to intermittent INVALID IPNs.
This particular issue has been resolved.
We apologize for any impact caused by these incidents.
PayPal Merchant Technical Support Team
If you have questions, contact PayPal Merchant Technical
Support by going to https://www.paypal.com/mts and filing a
ticket under Contact Support.