IPN can be blocked or resticted by your server settings, theme or other plugins. The good news is you can simulate the notifications to check if all is working.
To carry out a simulation:
- Enable the PayPal Sandbox on the plugin setup page
- Fill in and send your payment form (you do not need to make an actual payment)
- Go to the Payments Report and copy the long number in the last column from the payment you have just made
- Go to the IPN simulation page: https://developer.paypal.com/developer/ipnSimulator
- Login and enter the IPN listener URL
- Select ‘Express Checkout’ from the drop down
- Scroll to the bottom of the page and enter the long number you copied at step 3 into the ‘Custom’ field
- Click ‘Send IPN’. Scroll up the page and you should see an ‘IPN Verified’ message.
- Go back to your Payments Report and refresh, you should now see the payment completed message