Error email from PayPal

Hello,

I have been receiving the following email from PayPal each time I receive a payment through your plugin.

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

https://moderncooking.us9.list-manage.com/subscribe/paypal-ipn?u=9e6cc….

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.

PROTECT YOUR PASSWORD

NEVER give your password to anyone, including PayPal employees. Protect yourself against fraudulent websites by opening a new web browser (e.g. Internet Explorer or Firefox) and typing in the PayPal URL every time you log in to your account.

Copyright ? 1999-2020 PayPal. All rights reserved.

PayPal (Europe) S.à r.l. et Cie, S.C.A. Société en Commandite par Actions Registered Office: 22–24 Boulevard Royal, L-2449 Luxembourg RCS Luxembourg B 118 349

PayPal RT000111:en_US(en-DE):1.0.0:74d9725d5640e

Do you have any tips on how to fix this??