I have a billing agreement setup with the buyer. If buyer cancels the agreement by logging in his paypal account, how would I come to know about it? Does paypal sends some IPN or is there any API call which can be used to check whether billing agreement has been cancelled or not?
Paypal will send two different IPN's. First it will notify you of the agreement cancellation with a subscr_cancel IPN and at the end of the billing cycle (when no other payment will be done due to the cancellation) it will send you a subscr_eot for you to take whatever action is required (cancel your user subciption for example).
