PayPal integration (IPN) - Just how possible is it REALLY?

Question

I've spent MONTHS trying to integrate PayPal into my site, followed countless tutorials, articles - read all the docs, downloaded countless samples and so-called "complete, working samples" and have yet to get it working.

I've also asked a few questions on separate occasions, right here on S/O (under an old, now cancelled account) which didn't lead to any correct answers.

I just came across the www.x.com website, and was reading through it. I'm going to give it one more attempt, but before I do so, I'd like to know if,

How to get started 1.Check your account status. Login to PayPal. Go to your PayPal Profile and click My settings. Confirm that your “Account type” is either Premier or Business, or upgrade your account.

2.Check your API settings. Click My selling tools. Expand “Selling online” if needed and check “API access.” Click Update and Add or edit API permission or View API signature.

3.In your PayPal Profile, click My selling tools, click Instant Payment Notification. Follow the instructions to enable your IPN including entering your Notification URL.

4.To create a basic IPN listener script, use the PayPal IPN script generator. If necessary, modify the script to meet your needs.

5.Install the script on your website at the Notification URL you specified in your PayPal Profile. 6.Test your script using the PayPal Sandbox. (Registration is free.)

7.Once you’ve verified that your implementation works correctly in the Sandbox, you’re now ready to go live.

That above quoted text, (from https://www.x.com/developers/paypal/products/instant-payment-notification ) really is all I need, as it says?

Are there other things that are involved that the documentation does not cover, or are there other things that one would need to know in order to integrate PayPal IPN into their website, which are not easily accessible via the PayPal or X.com websites?

Piscatorial

So what's exactly is not working? I've implemented IPN on countless websites without any problems. – Cyaneous

It never goes to "VERIFIED". It always goes to "FAILED". Also; the post data paypal sends back is never what they say it will be, so when I change in my code, it still falls through to the "FAILED" clause. I've posted full code on several questions here and nobody could seem to find any issues... Eventually people stop trying to help, probably because they're unsure of what to do/try next, like myself. I've tried contacting PayPal... As expected, I did not receive a response. – Piscatorial

I've even tried all the samples (in different languages, too!) that PayPal and x.com give you - but they never work. – Piscatorial

jase there are examples even here on SO for ipn - #9852670 #3726252 #6225534 – Sheepish

@Sheepish - thank you :-) (I did try several ones on here though). – Piscatorial

@Piscatorial The IPN is working very well and for years. Locate what you make wrong. – Sheepish

Answer 1

The most common problem for not receiving VERIFIED is that you are sending the IPN packet back to PayPal in the incorrect order. It must be exact with no variations of any kind, and you must remember to also attach &cmd=_notify-validate to the request query string.

Carnahan

&cmd=_notify-validate - now that's something I'm almost certain I haven't seen in a lot of the samples I've collected! Thank you for your answer, I will attempt to have another go and see what happens. – Piscatorial