If you are getting "PayPal Instant Payment Notification Warning" notifications that look like the below. 

___________________________________
From: service@intl.paypal.com
​
Subject: PayPal Instant Payment Notification Warning
​
Hello ,
​
Please check your server that handles PayPal Instant Payment Notifications
(IPN). IPNs sent to the following URL(s) are failing:
​
{Your website address url}
​
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.
​
Thanks,
​
PayPal
​
___________________________________

These are usually from an old website or your legacy Evolution store. You can easily disable them as seen below. 

Check and update your notifications settings in Paypal. Simply login and go to account settings and then find IPN ( Instant Payment Notifications ). You can disable them or remove the old url. 

Now turn off the notifications

​
That's it you should stop receiving these from here forward.