如果用户批准预批准付款，然后前往 PayPal 取消预批准付款，PayPal 是否会向我的应用程序发送任何类型的通知，让我知道该付款已被取消？
以下是有关此事的一些文档:Paypal Preapproval API Operation
最佳答案
PayPal sends an IPN message in response to a payment, a refund, creation of a preapproval, and cancellation of a preapproval. Your IPN message handler must be set up in the way described in the Instant Payment Notification Guide.
关于notifications - 当有人取消预先批准的付款时，PayPal 会发送通知吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/10894517/