If you got email from PayPal with subject line "PayPal Instant Payment Notification Warning" and the body says something similar to the text below, you can fix it from your PayPal account area. Dear Name, Please check your server that handles PayPal Instant Payment Notifications (IPN). Instant Payment Notifications sent to the following URL(s) are failing: http://yourdomainname.com/someurl.... 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,...