In my PHP code for handling the IPN, everything works fine, except for one line:
$email = $_GET['ipn_email'];
This was in the example code they offer in order to get you started. I assumed it would retrieve the email address that was associated with the administrator of the Paypal account doing the billing.
However, it seems to never get set. If I use the code above, my IPN script fails. The only way my IPN script works is if I simply set $email to some arbitrary email address of my choosing.
Is is okay for me to just set my own email address? Should I be getting an ipn_email value from GET data? What is the value of ipn_email supposed to be?
$_GET[] variables are retrieved from the querystring within the url. Therefore to send set the one your asking the user must request
host/page.html?ipn_email=an_email_address
If your not sending that format to the server the variable will never be set.
Not sure if you used this tutorial but it explains one reason for using it