Mike Jolley has developed a quick snippet/plugin/dropin that will tell you if your IPN is going to work when PayPal makes the switch to SHA-156.
Instant Payment Notification (IPN) is a message service that automatically notifies merchants of events related to PayPal transactions. For example, you’re using WooCommerce and a customer is taken to the PayPal website to pay for your product. When the payment is complete, PayPal sends a notification to your website telling WooCommerce to mark the order as paid. This isn’t just a WooCommerce thing, many plugins that integrate with PayPal use IPN.
To check your WordPress website for compatibility with the new IPN, you can upload Mike’s plugin.
Get code: https://gist.github.com/mikejolley/0941e0882efcad64ea40
