PayPal Instant Payment Notifications Email?

Received the following email from PayPal. Is there an updated setting I need to apply in Funnelish or do I need to switch to v2?

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.

Should we still be using V1 or V2 Paypal?

We are having issues with V1 currently not showing sales in CF or Funnelish.