On Paypal Sandbox:
After logging in using a test account and then clicking the "Pay Now" button, the user is redirected to "Thanks for your order" page inside Paypal. The page has three(3) links below the message that says:
Return to Test Store
Go to PayPal account overview
Add funds from your bank
Clicking the "Return to Test Store" will redirect me to the return URL I specified on my query string. This marks the order as "Completed" or whatever the value of the payment_status returned by Paypal is.
The Problem: Clicking the other links bypasses the return URL and goes to user account profile which leaves the order incomplete even if the transaction was successfully paid because the return URL has the script to mark the outcome of the transaction.
The Question: Is there a way to bypass the Thank you page and just redirect to my return URL so the transaction can be concluded accordingly?
BTW, I have my Test Business Account set to autoredirect to the return URL after the order.
You want to read about PayPal's Instant Payment Notification and about Identifying Your IPN Listener to PayPal.
You have the option to be notified whenever a transaction takes place, regardless of what users clicks on. Paypal's servers will make requests to a Notification URL you provide and give you informations about that transaction.
来源：https://stackoverflow.com/questions/6039861/paypal-payment-standard-callback-url