HTTPS postback requirement for PayPal IPN
Message from PayPal
PayPal recently notified merchants using PayPal’s Instant Payment Notification (IPN) service, that they will need to ensure HTTPS is being used when posting the message back to PayPal for verification. HTTP postbacks will no longer be supported.
What does this mean for you?
Your site is required to use HTTPS to utilize PayPal's IPN. Only HTTPS will be allowed for postbacks to PayPal.
Is your site is already set to use HTTPS?
Yes! That's great, no further action is required.
Not yet. If your site is not currently set to use HTTPS you will be required to obtain an SSL certificate to continue using PayPal's IPN. Please reach out to your hosting provider for more details.
Additional information is available on PayPal's website.