PayPal IPN question

[ecm2000]

In my IPN handler when I receive msg 'Completed' from PayPal server I just want to refuse the transaction which PayPal just completed just because I see that

amount is tampered. How can I acknowledge to PayPal server to not to complete this transaction?

Is there way I can acknowledge to PayPal server if operation on my end is completed or not

[rocknbil]

Welcome aboard ecm2000, the problem is when you receive "competed" via IPN it's already done.

I would investigate how the amount is getting tampered with.

[ecm2000]

Even if the amount is not tampered. There could be other reason that I want same notification again because my code could not connect to the my DB to finish the work on my end. I don't see PayPal server requires any acknowledgment from my end to complete or rollback the transaction. PayPal server should not Complete it unless I reply with OK. If I don't reply with OK(Due whatever reason), transaction should be rolled back.

[rocknbil]

I don't have an answer to that, but if I were to want this kind of functionality, the first place I would look is in my payPal account to see if I can locate a setting to require approval of transactions before accepting them. It's likely in there.