Paypal Instant Notification Warning


I have been getting these message from Paypal lately.

Please check your server that handles PayPal Instant Payment Notifications (IPN). IPNs sent to the following URL(s) are failing:

If you do not recognize this URL, you may be using a service provider that is using IPN on your behalf. Please contact your service provider with the above information. If this problem continues, IPNs may be disabled for your account.

This has been happening since the upgrade to Membership 2. From what I can tell the URL is different for members that joined before the upgrade. In the IPN settings I am using the new URL and it works fine for new members.

I can't see anyway to update the URL for the older members. Is there anyway to get around this?