Reply To: Confused about implementing PayPal

The verification of the payment is handled in the background with a call from paypal to the IPN file and has nothing to do with the redirection after payment.
In the paypal settings is a log of the IPN calls that can lead you to why it hasn’t happened or if it happened why it wasn’t successful.
Further you can define the URL of the IPN script manually, which shouldn’t be necessary but helped me one time too. The URL to enter would be /wp-config/plugins/easyreservations/lib/modules/paypal/paypal_ipn.php

Further it can happen that the verification won’t work in sandbox, but does in live mode. It was reported once, but I couldn’t replicate it till now. That SSL has to be activated in sandbox is the only requirement I’m sure of.