I received the following email from PayPal:
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.
Thank you for your prompt attention to this issue.
Click Profile on the My Account tab. Click Instant Payment Notification Preferences in the Selling Preferences column. Click Choose IPN Settings to specify your listener's URL and activate the listener.
Okay, I login into PayPal, click Profile, but I can't find Selling Preferences column and Instant Payment Notification Preferences.
So I wonder what this notification means and why I received this message?