Why I am getting Emails from PayPal stating Instant Payment Notifications sent to the URL(s) are failing?

If you are using a PayPal Payment method, you may see an email from PayPal stating below:
“Please check your server that handles PayPal Instant Payment Notification(IPN). IPNs sent to the following URL(s) are failing: http://yourstore.com/paypal/ipn/. 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 can happen when the Instant Payment Notification is turned on in your PayPal account. If you turn this off, you will stop receiving those emails from PayPal.
You will be able to find more details about how to fix it in this third-party article below:
Please Note: IPN Url is required for PayPal Website Payments Standard Payment method.
Though we have seen that the steps mentioned in the above article resolves the issue, we do not guarantee that it will always work. If you are still seeing the issue after turning the PayPal Instant Payment Notification off, then please contact PayPal Support for assistance.