When someone starts a recurring subscription, i pass on the custom variable which contains the User ID of the user on my system. After the payment I receive two IPNs, subscr_signup and subscr_payment. Both have the custom variable in them which lets me identify the user.
However, for future recurring payments, will the IPN continue to pass on the custom variable? Should I rely on the subscr_id instead of custom?
Thanks.
I found the answer from this page. Yes, the custom variable will always be passed as-is in every consecutive IPN post.
Quote:
Custom is passed back through both the signup and payment IPN posts and is passed back through the consecutive IPN posts. There is not a variable that is passed back in the first payment IPN that is not reproduced in the consecutive ones. The only distinguishable factor would be the sign-up or if there was a different price for the first period of payment.
来源：https://stackoverflow.com/questions/486626/paypal-recurring-subscriptions-question